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A008299 Triangle of associated Stirling numbers of second kind. 19
1, 1, 1, 3, 1, 10, 1, 25, 15, 1, 56, 105, 1, 119, 490, 105, 1, 246, 1918, 1260, 1, 501, 6825, 9450, 945, 1, 1012, 22935, 56980, 17325, 1, 2035, 74316, 302995, 190575, 10395, 1, 4082, 235092, 1487200, 1636635, 270270, 1, 8177, 731731, 6914908, 12122110 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

COMMENTS

T(n,k) is the number of set partitions of [n] into k blocks of size at least 2. Compare with A008277 (blocks of size at least 1) and A059022 (blocks of size at least 3). See also A200091. Reading the table by diagonals gives A134991. The row generating polynomials are the Mahler polynomials s_n(-x). See [Roman, 4.9]. Rows are of lengths 1,1,2,2,3,3,....

For a relation to decomposition of spin correlators see Table 2 of the Delfino and Vito paper. - Tom Copeland, Nov 11 2012

REFERENCES

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 222.

A. E. Fekete, Apropos two notes on notation, Amer. Math. Monthly, 101 (1994), 771-778.

J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 76.

S. Roman, The Umbral Calculus, Dover Publications, New York (2005), pp. 129-130.

LINKS

Vincenzo Librandi and Alois P. Heinz, Rows n = 2..200, flattened (rows n = 2..104 from Vincenzo Librandi)

P. Bala, Diagonals of triangles with generating function exp(t*F(x)).

J. Fernando Barbero G., Jesús Salas, Eduardo J. S. Villaseñor, Bivariate Generating Functions for a Class of Linear Recurrences. I. General Structure, arXiv:1307.2010, 2013

Gesualdo Delfino and Jacopo Viti, Potts q-color field theory and scaling random cluster model, arXiv:1104.4323, 2011.

L. M. Smiley, Completion of a Rational Function Sequence of Carlitz

Eric Weisstein's World of Mathematics, Mahler polynomial

Wikipedia, Mahler polynomials

FORMULA

E.g.f. with additional constant 1: exp(t*(exp(x)-1-x)) = 1+t*x^2/2!+t*x^3/3!+(t+3*t^2)*x^4/4!+....

Recurrence relation: T(n+1,k) = k*T(n,k) + n*T(n-1,k-1).

T(n,k) = A134991(n-k,k); A134991(n,k) = T(n+k,k).

More generally, if S_r(n,k) counts the number of set partitions of [n] into k blocks of size at least r then we have the recurrence S_r(n+1,k)=k*S_r(n,k)+binomial(n,r-1)*S_r(n-r+1,k-1) (for this sequence, r=2), with associated e.g.f.: sum(S_r(n,k)*u^k*(t^n/n!), n=0..infty, k=0..infty)=exp(u*(e^t-sum(t^i/i!, i=0..r-1))).

T(n,k) = sum_{i=0..k} (-1)^i*binomial(n, i)*[sum_{j=0..k-i} (-1)^j*(k -i -j)^(n-i)/(j!*(k-i-j)!)] - David Wasserman, Jun 13 2007

G.f.: (R(0)-1)/(x^2*y), where R(k) = 1 - (k+1)*y*x^2/( (k+1)*y*x^2 -(1- k*x)*(1-x - k*x)/R(k+1) ); (continued fraction). - Sergei N. Gladkovskii, Nov 09 2013

EXAMPLE

There are 3 ways of partitioning a set N of cardinality 4 into 2 blocks each of cardinality at least 2, so S_2(4,2)=3. Table begins

.n\k.|..1....2.....3.....4

= = = = = = = = = = = = = =

..2..|..1

..3..|..1

..4..|..1....3

..5..|..1...10

..6..|..1...25....15

..7..|..1...56...105

..8..|..1..119...490...105

..9..|..1..246..1918..1260

...

Reading the table by diagonals produces the triangle A134991.

MATHEMATICA

t[n_, k_] := Sum[ (-1)^i*Binomial[n, i]*Sum[ (-1)^j*(k - i - j)^(n - i)/(j!*(k - i - j)!), {j, 0, k - i}], {i, 0, k}]; Flatten[ Table[ t[n, k], {n, 2, 14}, {k, 1, Floor[n/2]}]] (* Jean-François Alcover, Oct 13 2011, after David Wasserman *)

CROSSREFS

Rows give A000247, A000478, A058844.

Cf. A059022, A059023, A059024, A059025.

Row sums: A000296. A134991. A200091.

Sequence in context: A211360 A178866 A019427 * A016478 A102430 A135573

Adjacent sequences:  A008296 A008297 A008298 * A008300 A008301 A008302

KEYWORD

nonn,tabf,nice

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Formula and cross-references from Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Dec 14 2000

More terms from David Wasserman, Jun 13 2007

Edited by Peter Bala, Dec 04 2011

STATUS

approved

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Last modified September 19 18:34 EDT 2014. Contains 246978 sequences.