cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A172040 Triangle T(n,k), read by rows, given by [0,1,2,1,2,1,2,1,2,1,2,...] DELTA [2,0,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 2, 0, 2, 4, 0, 6, 8, 8, 0, 22, 28, 24, 16, 0, 90, 112, 96, 64, 32, 0, 394, 484, 416, 288, 160, 64, 0, 1806, 2200, 1896, 1344, 800, 384, 128, 0, 8558, 10364, 8952, 6448, 4000, 2112, 896, 256, 0, 41586, 50144, 43392, 31616, 20160, 11264, 5376, 2048, 512, 0
Offset: 0

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Author

Philippe Deléham, Jan 23 2010

Keywords

Comments

Riordan array (1, 2x*f(x)) where f(x) is the g.f. of A001003. Riordan production matrix is : (0, (2-x)/(1-x)).

Examples

			Triangle begins:
  1 ;
  0,2 ;
  0,2,4 ;
  0,6,8,8 ;
  0,22,28,24,16 ; ...
		

Crossrefs

Formula

Sum_{k=0..n} T(n,k) = A006318(n).

A183875 Triangle T(n,k) for A(x)^k=sum(n>=k T(n,k)*x^n), where o.g.f. A(x) satisfies A(x)=(a+b*x*A(x))/(c-d*x*A(x)), a=1,b=2,c=1,d=2.

Original entry on oeis.org

1, 4, 1, 24, 8, 1, 176, 64, 12, 1, 1440, 544, 120, 16, 1, 12608, 4864, 1168, 192, 20, 1, 115584, 45184, 11424, 2112, 280, 24, 1, 1095424, 432128, 113088, 22528, 3440, 384, 28, 1, 10646016, 4227584, 1133952, 237824, 39840, 5216, 504, 32, 1, 105522176, 42115072, 11506944, 2505728, 448064, 65280, 7504, 640, 36, 1
Offset: 1

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Author

Vladimir Kruchinin, Feb 12 2011

Keywords

Comments

For o.g.f G(x), G(A(x,a,b,c,d))=g(0)+sum(n>0, sum(k=1..n, T(n,k,a,b,c,d)*g(k))x^n).
T(n,k,1,1,1,1)=A080247(n,k),
T(n,k,2,-1,1,1)=A108891(n,k),
T(n,k,1,-2,1,1)=A125692(n,k),
T(n,k,1,-3,1,1)=A125694(n,k),
T(n,k,-2,1,1,1)=A085403(n,k).

Examples

			1,
4,1,
24,8,1,
176,64,12,1,
1440,544,120,16,1,
12608,4864,1168,192,20,1,
115584,45184,11424,2112,280,24,1,
1095424,432128,113088,22528,3440,384,28,1,
10646016,4227584,1133952,237824,39840,5216,504,32,1,
105522176,42115072,11506944,2505728,448064,65280,7504,640,36,1
		

Programs

  • Mathematica
    T[n_, k_, a_, b_, c_, d_] := k/n Sum[Binomial[n, n - k - i] a^(k + i) b^(n - k - i) Binomial[i + n - 1, n - 1] c^(-i - n) d^i, {i, 0, n - k}];
    T[n_, k_] := T[n, k, 1, 2, 1, 2];
    Table[T[n, k], {n, 1, 10}, {k, 1, n}] // Flatten (* Jean-François Alcover, Aug 08 2018, from formula *)

Formula

T(n,k,a,b,c,d):=k/n*sum(i=0..n-k, binomial(n,n-k-i)*a^(k+i)*b^(n-k-i)*binomial(i+n-1,n-1)*c^(-i-n)*d^i), a,b,c,d !=0, n>0.
T(n,k,1,2,1,2):=k/n*2^(n-k)*sum(i=0..n-k, binomial(n,n-k-i)*binomial(i+n-1,n-1)), n>0.
Conjecture: T(n,1) = A156017(n-1). - R. J. Mathar, Nov 14 2011
Showing 1-2 of 2 results.