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A084938 Triangle read by rows: T(n,k) = Sum_{j>=0} j!*T(n-j-1, k-1) for n >= 0, k >= 0. 625
1, 0, 1, 0, 1, 1, 0, 2, 2, 1, 0, 6, 5, 3, 1, 0, 24, 16, 9, 4, 1, 0, 120, 64, 31, 14, 5, 1, 0, 720, 312, 126, 52, 20, 6, 1, 0, 5040, 1812, 606, 217, 80, 27, 7, 1, 0, 40320, 12288, 3428, 1040, 345, 116, 35, 8, 1, 0, 362880, 95616, 22572, 5768, 1661, 519, 161, 44 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,8

COMMENTS

Triangle T(n,k) is [0,1,1,2,2,3,3,4,4,...] DELTA [1,0,0,0,0,0.....] = A110654 DELTA A000007.

T(n,k) = number of permutations on [n] that (i) contain a 132 pattern only as part of a 4132 pattern and (ii) start with n+1-k. For example, for n>=1, T(n,1) = (n-1)! counts all (n-1)! permutations on [n] that start with n: either they avoid 132 altogether or the initial entry serves as the "4" in a 4132 pattern and T(4,3) = 3 counts 2134, 2314, 2341. - David Callan, Jul 20 2005

T(n,k) is the number of permutations on [n] that (i) contain a (scattered) 342 pattern only as part of a 1342 pattern and (ii) contain 1 in position k. For example, T(4,3) counts 3214, 4213, 4312. (It does not count, say, 2314 because 231 forms an offending 342 pattern.) - David Callan, Jul 20 2005

This triangle * [1,2,3,...] = A134378: (1, 2, 5, 14, 44, 158, 663, ...) = row sums of triangle A134379. - Gary W. Adamson, Oct 22 2007

Riordan array (1,x*g(x)) where g(x) is the g.f. of the factorials (n!). - Paul Barry, Sep 25 2008

Modulo 2, this sequence becomes A106344 .

In general, the triangle [r_0,r_1,r_2,r_3,...] DELTA [s_0,s_1,s_2,s_3,...] has generating function 1/(1-(r_0*x+s_0*x*y)/(1-(r_1*x+s_1*x*y)/(1-(r_2*x+s_2*x*y)/1-(r_3*x+s_3*x*y)/(1-...(continued fraction).

Eigensequence of the triangle = A165489: (1, 1, 2, 6, 23, 105, 550, 3236, ...). - Gary W. Adamson, Sep 20 2009

T(n,k) is the number of permutations of {1,2,...,n} having k cycles such that the elements of each cycle of the permutation form an interval. - Ran Pan, Nov 11 2016

LINKS

T. D. Noe, Rows n = 0..100 of triangle, flattened

P. Barry, A Note on a One-Parameter Family of Catalan-Like Numbers, JIS 12 (2009) 09.5.4

P. Barry, Continued fractions and transformations of integer sequences, JIS 12 (2009) 09.7.6

David Callan, A combinatorial interpretation of the eigensequence for composition, arXiv:math/0507169 [math.CO], 2005.

David Callan, A Combinatorial Interpretation of the Eigensequence for Composition, Journal of Integer Sequences, Vol. 9 (2006), Article 06.1.4.

H. Fuks and J. M. G. Soto, Exponential convergence to equilibrium in cellular automata asymptotically emulating identity, arXiv preprint arXiv:1306.1189 [nlin.CG], 2013.

Peter Luschny, Transformations of integer sequences.

R. J. Mathar, Properties of Deleham's Delta Transformation: OEIS A084938

FORMULA

T(k,k) = 1;

T(k+1,k) = A001477(k);

T(k+2,k) = A000096(k);

T(n+1,1) = A000142(n);

T(n+2,2) = A003149(n);

T(n+3,3) = A090595(n);

T(n+4,4) = A090319(n).

# The operator DELTA takes two sequences r = (r_0, r_1, ...), s = (s_0, s_1, ...) and produces a triangle T(n, k), 0 <= k <= n, as follows:

Let q(k) = x*r_k + y*s_k for k >= 0; let P(n, k) (n >= 0, k >= -1) be defined recursively by P(0, k) = 1 for k >= 0; P(n, -1) = 0 for n >= 1; P(n, k) = P(n, k-1) + q(k)*P(n-1, k+1) for n >= 1, k >= 0.

Then P(n, k) is a homogeneous polynomial in x and y of degree n and T(n, k) = coefficient of x^(n-k)*y^k in P(n, 0).

T(m+n, m)= Sum_{k=0..n} A090238(n, k)*binomial(m, k).

G.f. for column k: Sum_{n>=0} T(k+n, k)*x^n = (Sum_{n>=0} n!*x^n )^k.

For k>0, T(n+k, k) = Sum_{a_1 + a_2 + .. + a_k = n} (a_1)!*(a_2)!*..*(a_k)!; a_i>=0, n>=0.

T(n,k)= Sum_{j>=0} A075834(j)*T(n-1,k+j-1).

EXAMPLE

From Paul Barry, Sep 25 2008: (Start)

Triangle [0,1,1,2,2,3,3,4,4,5,5,...] DELTA [1,0,0,0,0,...] begins

1,

0,      1,

0,      1,     1,

0,      2,     2,     1,

0,      6,     5,     3,    1,

0,     24,    16,     9,    4,    1,

0,    120,    64,    31,   14,    5,   1,

0,    720,   312,   126,   52,   20,   6,   1,

0,   5040,  1812,   606,  217,   80,  27,   7,  1,

0,  40320, 12288,  3428, 1040,  345, 116,  35,  8, 1,

0, 362880, 95616, 22572, 5768, 1661, 519, 161, 44, 9, 1 (End)

From Paul Barry, May 14 2009: (Start)

The production matrix is

0,   1,

0,   1,  1,

0,   1,  1, 1,

0,   2,  1, 1, 1,

0,   7,  2, 1, 1, 1,

0,  34,  7, 2, 1, 1, 1,

0, 206, 34, 7, 2, 1, 1, 1

which is based on A075834. (End)

MAPLE

DELTA := proc(r, s, n) local T, x, y, q, P, i, j, k, t1; T := array(0..n, 0..n);

for i from 0 to n do q[i] := x*r[i+1]+y*s[i+1]; od: for k from 0 to n do P[0, k] := 1; od: for i from 0 to n do P[i, -1] := 0; od:

for i from 1 to n do for k from 0 to n do P[i, k] := sort(expand(P[i, k-1] + q[k]*P[i-1, k+1])); od: od:

for i from 0 to n do t1 := P[i, 0]; for j from 0 to i do T[i, j] := coeff(coeff(t1, x, i-j), y, j); od: lprint( seq(T[i, j], j=0..i) ); od: end;

# To produce the current triangle: s3 := n->floor((n+1)/2); s4 := n->if n = 0 then 1 else 0; fi; r := [seq(s3(i), i= 0..40)]; s := [seq(s4(i), i=0..40)]; DELTA(r, s, 20);

MATHEMATICA

a[0, 0] = 1; a[n_, k_] := a[n, k] = Sum[j! a[n - j - 1, k - 1], {j, 0, n - 1}]; Flatten[Table[a[i, j], {i, 0, 10}, {j, 0, i}]] (* T. D. Noe, Feb 22 2012 *)

DELTA[r_, s_, m_] := Module[{p, q, t, x, y}, q[k_] := x*r[[k+1]] + y*s[[k+1]]; p[0, _] = 1; p[_, -1] = 0; p[n_ /; n >= 1, k_ /; k >= 0] := p[n, k] = p[n, k-1] + q[k]*p[n-1, k+1] // Simplify; t[n_, k_] := Coefficient[p[n, 0], x^(n-k)*y^k]; t[0, 0] = p[0, 0]; Table[t[n, k], {n, 0, m}, {k, 0, n}]]; DELTA[Floor[Range[10]/2], Prepend[Table[0, {10}], 1], 10] (* Jean-François Alcover, Sep 12 2013, after Philippe Deléham *)

PROG

(Sage)

def delehamdelta(R, S) :

    L = min(len(R), len(S)) + 1

    A = [SR(R[k] + x*S[k]) for k in range(L-1)]

    C = [SR(1) for i in range(L+1)]; C[0] = SR(0)

    for k in (1..L) :

        for n in range(k-1, 0, -1) :

            C[n] = C[n-1] + C[n+1]*A[n-1]

        p = expand(C[1])

        print [p.coefficient(x, n) for n in (0..k-1)]

def A084938_triangle(n) :

    return delehamdelta([(i+1)//2 for i in (0..n)], [0^i for i in (0..n)])

A084938_triangle(10) # Peter Luschny, Jan 28 2012

CROSSREFS

Cf. A001477, A000096, A000142, A003149, A090595, A090319.

Cf. A051295 (row sums), A090238, A134378, A134379.

Diagonals: A000007, A000142, A003149, A090595, A090319 ; A000012, A001477, A000096, A092286, A090386, A090391, A090392, A090393, A090394.

Cf. A165489, A165490. - Gary W. Adamson, Sep 20 2009

Sequence in context: A110314 A152882 A130167 * A135898 A131182 A254883

Adjacent sequences:  A084935 A084936 A084937 * A084939 A084940 A084941

KEYWORD

nonn,tabl

AUTHOR

Philippe Deléham, Jul 16 2003; corrections Dec 17 2008, Dec 20 2008, Feb 05 2009

EXTENSIONS

Name edited by Derek Orr, May 01 2015

STATUS

approved

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Last modified May 26 18:43 EDT 2017. Contains 287129 sequences.