

A134991


Triangle of Ward numbers T(n,k) read by rows.


22



1, 1, 3, 1, 10, 15, 1, 25, 105, 105, 1, 56, 490, 1260, 945, 1, 119, 1918, 9450, 17325, 10395, 1, 246, 6825, 56980, 190575, 270270, 135135, 1, 501, 22935, 302995, 1636635, 4099095, 4729725, 2027025, 1, 1012, 74316, 1487200, 12122110, 47507460
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,3


COMMENTS

This is the triangle of associated Stirling numbers of the second kind, A008299, read along the diagonals.
This is also a rowreversed version of A181996 (with an additional leading 1)  see the table on p. 92 in the Ward reference. A134685 is a refinement of the Ward table.
The first and second diagonals are A001147 and A000457 and appear in the diagonals of several OEIS entries. The polynomials also appear in Carlitz (p. 85), Drake et al. (p. 8) and Smiley (p. 7).
First few polynomials (with a different offset) are
P(0,t) = 0
P(1,t) = 1
P(2,t) = t
P(3,t) = t + 3 t^2
P(4,t) = t + 10 t^2 + 15 t^3
P(5,t) = t + 25 t^2 + 105 t^3 + 105 t^4
These are the "face" numbers of the tropical Grassmannian G(2,n),related to phylogenetic trees (with offset 0 beginning with P(2,t)). Corresponding hvectors are A008517.  Tom Copeland, Oct 03 2011
A133314 applied to the derivative of A(x,t) implies (a.+b.)^n = 0^n, for (b_n)=P(n+1,t) and (a_0)=1, (a_1)=t, and (a_n)=(1+t) P(n,t) otherwise. E.g., umbrally, (a.+b.)^2 = a_2*b_0 + 2 a_1*b_1 + a_0*b_2 =0.  Tom Copeland, Oct 08 2011
Beginning with the second column, the rows give the faces of the Whitehouse simplicial complex with the fourth order complex being three isolated vertices and the fifth order being the Petersen graph with 10 vertices and 15 edges (cf. Readdy).  Tom Copeland, Oct 03 2014
Stratifications of smooth projective varieties which are fine moduli spaces for stable npointed rational curves. Cf. pages 20 and 30 of the Kock and Vainsencher reference and references in A134685.  Tom Copeland, May 18 2017
Named after the American mathematician Morgan Ward (19011963).  Amiram Eldar, Jun 26 2021


REFERENCES

Louis Comtet, Advanced Combinatorics, Reidel, 1974, page 222.


LINKS

G. C. Greubel, Rows n = 1..65, flattened
J. Fernando Barbero G., Jesús Salas and Eduardo J. S. Villaseñor, Bivariate Generating Functions for a Class of Linear Recurrences, I: General Structure, Journal of Combinatorial Theory, Series A, Vol. 125 (2014), pp. 146165; arXiv preprint, arXiv:1307.2010 [math.CO], 20132014.
J. Fernando Barbero G., Jesús Salas and Eduardo J. S. Villaseñor, Bivariate Generating Functions for a Class of Linear Recurrences. II. Applications, arXiv preprint arXiv:1307.5624 [math.CO], 2013.
J. Fernando Barbero G., Jesús Salas and Eduardo J. S. Villaseñor, Generalized Stirling permutations and forests: Higherorder Eulerian and Ward numbers, Electronic Journal of Combinatorics, Vol. 22, No. 3 (2015), #P3.37.
Andreas Blass, Natasha Dobrinen and Dilip Raghavan, The next best thing to a ppoint, The Journal of Symbolic Logic, Vol. 80, No. 3 (2015), pp. 866900; arXiv preprint, arXiv:1308.3790 [math.LO], 2013.
D. Callan, T. Mansour, and M. Shattuck Some identities for derangement and Ward number sequences and related bijections, Pure Mathematics and Applications, Vol. 25 (Edition 2), pp. 132143, 2015.
L. Carlitz, The coefficients in an asymptotic expansion and certain related numbers, Duke Math. J., Vol. 35, No. 1 (1968), pp. 8390.
Lane Clark, Asymptotic normality of the Ward numbers, Discrete Math. 203 (1999), no. 13, 4148. [From N. J. A. Sloane, Feb 06 2012]
Tom Copeland, Generators, Inversion, and Matrix, Binomial, and Integral Transforms.
Satyan L. Devadoss, Daoji Huang and Dominic Spadacene, Polyhedral covers of tree space, SIAM Journal on Discrete Mathematics, Vol. 28, No. 3 (2014), pp. 15081514; arXiv preprint, arXiv:1311.0766 [math.CO], 2013.
S. Devadoss and J. Morava, Diagonalizing the genome I: navigation in tree spaces, arXiv:1009.3224v2 [math.AG], 2012.
S. Devadoss and O. Schuh, Cartography of Tree Space, Leonardo (MIT Press Direct), Vol. 53, Issue 3, 2019.
A. Dieckmann and E. Vigren, A New Result in Form of Finite Triple Sums for a Series from Ramanujan's Notebooks, Symmetry (2022) Vol. 14, No. 6, 1090.
Brian Drake, Ira M. Gessel and Guoce Xin, Three Proofs and a Generalization of the GouldenLitsynShevelev Conjecture on a Sequence Arising in Algebraic Geometry, J. of Integer Sequences, Vol. 10 (2007), Article 07.3.7.
Giovanni Gaiffi, Nested sets, set partitions and KirkmanCayley dissection numbers, arXiv preprint arXiv:1404.3395 [math.CO], 2014.
David M. Jackson, Achim Kempf and Alejandro H. Morales, A robust generalization of the Legendre transform for QFT, Journal of Physics A: Mathematical and Theoretical, Vol. 50, No. 22 (2017), 225201; arXiv preprint, arXiv:1612.0046 [hepth], 2017.
Bradley Robert Jones, On tree hook length formulae, Feynman rules and Bseries, Master's thesis, Math Dept., Simon Fraser University, 2014. p. 23.
Joachim Kock and Israel Vainsencher, Kontsevich's Formula for Rational Plane Curves, Recife, 1999 (version 31/01/2003).
Toufik Mansour and Mark Shattuck, A polynomial generalization of some associated sequences related to set partitions, Periodica Mathematica Hungarica, Vol. 75, No. 2 (December 2017), pp. 398412.
MathOverflow, Face numbers for tropical Grassmannian G'_2,7 simplicial complex?, 2011.
Andrew Elvey Price and Alan D. Sokal, Phylogenetic trees, augmented perfect matchings, and a Throntype continued fraction (Tfraction) for the Ward polynomials, arXiv:2001.01468 [math.CO], 2020.
Margaret A. Readdy, The preWDVV ring of physics and its topology, The Ramanujan Journal, Vol. 10, No. 2 (2005), pp. 269281; preprint, 2002.
Lucas Randazzo, Arboretum for a generalisation of Ramanujan polynomials, The Ramanujan Journal, Vol. 54 (2019), pp. 114; arXiv preprint, arXiv:1905.02083 [math.CO], 2019.
Lucas Randazzo, Combinatoire bijective autour d'arbres et de chemins, doctoral thesis, Université ParisEst, 2019.
Peter Regner, Phylogenetic Trees: Selected Combinatorial Problems, Master's Thesis, 2012, Institute of Discrete Mathematics and Geometry, TU Vienna, p. 52.
F. Ren, J. Yeh, and R. Zhou, ContextFree Grammars for Several Triangular Arrays, Axioms, Vol. 11, Issue 6, 297, 2022.
Leonard M. Smiley, Completion of a Rational Function Sequence of Carlitz, arXiv:math/0006106 [math.CO], 2000.
P. Théorêt, Fonctions génératrices pour une classe d'équations aux différences partielles, Ann. Sci. Math. Quebec 19, 91105 (1995).
Morgan Ward, The representations of Stirling's numbers and Stirling's polynomials as sums of factorials, Amer. J. Math., Vol. 56, No. 1 (1934), pp. 8795.
B. Zhu, Coefficientwise Hankeltotal positivity of rowgenerating polynomials for the mJacobiRogers triangle, arXiv:2202.03793 [math.CO], 2022.


FORMULA

E.g.f. for the polynomials is A(x,t) = (xt)/(t+1) + T{ (t/(t+1)) * exp[(xt)/(t+1)] }, where T(x) is the Tree function, the e.g.f. of A000169. The compositional inverse in x (about x = 0) is B(x) = x + t * [exp(x)  x  1]. Special case t = 1 gives e.g.f. for A000311. These results are a special case of A134685 with u(x) = B(x).
From Tom Copeland, Oct 26 2008: (Start)
UmbralSheffer formalism gives, for m a positive integer and u = t/(t+1),
[P(.,t)+Q(.,x)]^m = [m Q(m1,x)  t Q(m,x)]/(t+1) + sum(n>=1) { n^(n1)[u exp(u)]^n/n! [n/(t+1)+Q(.,x)]^m }, when the series is convergent for a sequence of functions Q(n,x).
Check: With t=1; Q(n,x)=0^n, for n>=0; and Q(1,x)=0, then [P(.,1)+Q(.,x)]^m = P(m,1) = A000311(m).
(End)
Let h(x,t) = 1/(dB(x)/dx) = 1/(1t*(exp(x)1)), an e.g.f. in x for row polynomials in t of A019538, then the nth row polynomial in t of the table A134991, P(n,t), is given by ((h(x,t)*d/dx)^n)x evaluated at x=0, i.e., A(x,t) = exp(x*P(.,t)) = exp(x*h(u,t)*d/du) u evaluated at u=0. Also, dA(x,t)/dx = h(A(x,t),t).  Tom Copeland, Sep 05 2011
The polynomials (1+t)/t*P(n,t) are the row polynomials of A112493. Let f(x) = (1+x)/(1x*t). Then for n >= 0, P(n+1,t) is given by t/(1+t)*(f(x)*d/dx)^n(f(x)) evaluated at x = 0.  Peter Bala, Sep 30 2011
From Tom Copeland, Oct 04 2011: (Start)
T(n,k) = (k+1)*T(n1,k) + (n+k+1)*T(n1,k1) with starting indices n=0 and k=0 beginning with P(2,t) (as suggested by a formula of David Speyer on MathOverflow).
T(n,k) = k*T(n1,k) + (n+k1)*T(n1,k1) with starting indices n=1 and k=1 of table (cf. Smiley above and Riordin ref.[10] therein).
P(n,t) = (1/(1+t))^n Sum_{k>=1} k^(n+k1) [(u*exp(u)]^k / k! with u=(t/(t+1)) for n>1; therefore, Sum_{k>=1} (1)^k k^(n+k1) x^k/k!
= [1+LW(x)]^(n) P{n,LW(x)/[1+LW(x)]}, with LW(x) the Lambert WFct.
T(n,k) = Sum_{i=0..k} ((1)^i binomial(n+k,i) Sum_{j=0..ki} (1)^j (kij)^(n+ki)/(j!(kij)!)) from relation to A008299. (End)
The e.g.f. A(x,t) = v * ( Sum_{j=>1} D(j1,u) (z)^j / j! ) where u = (xt)/(1+t), v = 1+u, z = x/((1+t) v^2) and D(j1,u) are the polynomials of A042977. dA/dx = 1/((1+t)(vA)) = 1/(1t*(exp(A)1)).  Tom Copeland, Oct 06 2011
The general results on the convolution of the refined partition polynomials of A134685, with u_1 = 1 and u_n = t otherwise, can be applied here to obtain results of convolutions of these polynomials.  Tom Copeland, Sep 20 2016
E.g.f.: C(u,t) = (ut)/(1+t)  W( ((t*exp((ut)/(1+t)))/(1+t)) ), where W is the principal value of the Lambert Wfunction.  Cheng Peng, Sep 11 2021
The function C(u,t) in the previous formula by Peng is precisely the function A(u,t) given in the initial 2008 formula of this section and the Oct 06 2011 formula from Copeland. As noted in A000169, Euler's tree function is T(x) = LambertW(x), where W(x) is the principal branch of Lambert's function, and T(x) is the e.g.f. of A000169.  Tom Copeland, May 13 2022


MATHEMATICA

t[n_, k_] := Sum[(1)^i*Binomial[n, i]*Sum[(1)^j*(kij)^(ni)/(j!*(kij)!), {j, 0, ki}], {i, 0, k}]; row[n_] := Table[t[k, kn], {k, n+1, 2*n}]; Table[row[n], {n, 1, 9}] // Flatten (* JeanFrançois Alcover, Apr 23 2014, after A008299 *)


CROSSREFS

Essentially the same as the triangle of associated Stirling numbers of the second kind, A008299.
A181996 is the mirror image.
Cf. A000457, A001147, A112493, A269939.
Sequence in context: A068438 A064060 A176740 * A212930 A225725 A095327
Adjacent sequences: A134988 A134989 A134990 * A134992 A134993 A134994


KEYWORD

nonn,tabl,changed


AUTHOR

Tom Copeland, Feb 05 2008


EXTENSIONS

Reference to A181996 added by N. J. A. Sloane, Apr 05 2012
Further edits by N. J. A. Sloane, Jan 24 2020


STATUS

approved



