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.

A102086 Triangular matrix, read by rows, that satisfies: T(n,k) = [T^2](n-1,k) when n>k>=0, with T(n,n) = (n+1).

Original entry on oeis.org

1, 1, 2, 3, 4, 3, 16, 20, 9, 4, 127, 156, 63, 16, 5, 1363, 1664, 648, 144, 25, 6, 18628, 22684, 8703, 1840, 275, 36, 7, 311250, 378572, 144243, 29824, 4200, 468, 49, 8, 6173791, 7504640, 2849400, 582640, 79775, 8316, 735, 64, 9, 142190703, 172785512
Offset: 0

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Author

Paul D. Hanna, Dec 29 2004

Keywords

Comments

Column 0 forms A082161. Column 1 forms A102087. Row sums form A102088.

Examples

			Rows of T begin:
[1],
[1,2],
[3,4,3],
[16,20,9,4],
[127,156,63,16,5],
[1363,1664,648,144,25,6],
[18628,22684,8703,1840,275,36,7],
[311250,378572,144243,29824,4200,468,49,8],
[6173791,7504640,2849400,582640,79775,8316,735,64,9],...
Matrix square T^2 equals T excluding the main diagonal:
[1],
[3,4],
[16,20,9],
[127,156,63,16],
[1363,1664,648,144,25],...
G.f. for column 0: 1 = (1-x) + 1*x*(1-x)(1-2x) + 3*x^2*(1-x)(1-2x)(1-3x) + ... + T(n,0)*x^n*(1-x)(1-2x)(1-3x)*..*(1-(n+1)*x) + ...
G.f. for column 1: 2 = 2(1-2x) + 4*x*(1-2x)(1-3x) + 20*x^2*(1-2x)(1-3x)(1-4x) + ... + T(n+1,1)*x^n*(1-2x)(1-3x)(1-4x)*..*(1-(n+2)*x) + ...
G.f. for column 2: 3 = 3(1-3x) + 9*x*(1-3x)(1-4x) + 63*x^2*(1-3x)(1-4x)(1-5x) + ... + T(n+2,2)*x^n*(1-3x)(1-4x)(1-5x)*..*(1-(n+3)*x) + ...
		

Crossrefs

Programs

  • Maple
    {T(n,k)=local(A=matrix(1,1),B);A[1,1]=1; for(m=2,n+1,B=matrix(m,m);for(i=1,m, for(j=1,i, if(j==i,B[i,j]=j,if(j==1,B[i,j]=(A^2)[i-1,1], B[i,j]=(A^2)[i-1,j]));));A=B);return(A[n+1,k+1])}
  • Mathematica
    T[n_, n_] := n+1; T[n_, k_] /; k>n = 0; T[n_, k_] /; k == n-1 := n^2; T[n_, k_] := T[n, k] = Coefficient[1-Sum[T[i, k]*x^i*Product[1-(j+k)*x, {j, 1, i-k+1}], {i, k, n-1}], x, n]; Table[T[n, k], {n, 0, 9}, {k, 0, n}] // Flatten (* Jean-François Alcover, Dec 15 2014, after PARI script *)
  • PARI
    {T(n,k)=if(n
    				

Formula

T(n, 0) = A082161(n) for n>0, with T(0, 0) = 1.
G.f. for column k: T(k, k) = k+1 = Sum_{n>=0} T(n+k, k)*x^n*prod_{j=1, n+1} (1-(j+k)*x).