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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A097750 Reversal of the binomial transform of the Whitney triangle A004070 (see A131250), triangle read by rows, T(n,k) for 0 <= k <= n.

Original entry on oeis.org

1, 1, 2, 1, 4, 4, 1, 6, 11, 8, 1, 8, 22, 26, 16, 1, 10, 37, 64, 57, 32, 1, 12, 56, 130, 163, 120, 64, 1, 14, 79, 232, 386, 382, 247, 128, 1, 16, 106, 378, 794, 1024, 848, 502, 256, 1, 18, 137, 576, 1471, 2380, 2510, 1816, 1013, 512, 1, 20, 172, 834, 2517, 4944, 6476, 5812, 3797, 2036, 1024
Offset: 0

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Author

Paul Barry, Aug 23 2004

Keywords

Comments

Reversal of the Riordan array (1/(1-2x), x/(1-x)^2), see A131250. Row sums are A061667 and diagonal sums of A131250 are A045623. The n-th row elements correspond to the end elements of the 2n-th row of the Whitney triangle A004070. A131250 corresponds to the product of Pascal's triangle and the Whitney triangle.

Examples

			Triangle begins:
1;
1, 2;
1, 4, 4;
1, 6, 11, 8;
1, 8, 22, 26, 16;
1, 10, 37, 64, 57, 32;
1, 12, 56, 130, 163, 120, 64;
1, 14, 79, 232, 386, 382, 247, 128;
		

Crossrefs

Row sums are A061667.

Programs

  • Maple
    T := (n,k) -> binomial(2*n-k, k)*hypergeom([1, 1, -k], [1, 1-2*k+2*n], -1):
    for n from 0 to 8 do seq(simplify(T(n, k)), k=0..n) od; # Peter Luschny, Oct 28 2018
  • Mathematica
    T[, 0] = 1; T[n, n_] := 2^n; T[n_, k_] /; 0 < k < n := T[n, k] = T[n - 1, k] + 2 T[n - 1, k - 1] - T[n - 2, k - 2]; T[, ] = 0;
    Table[T[n, k], {n, 0, 10}, {k, 0, n}] (* Jean-François Alcover, Jun 19 2019 *)

Formula

T(n, k) = Sum_{i=0..n} binomial(n+k, i-k).
T(n, k) = T(n-1,k)+2*T(n-1,k-1)-T(n-2,k-2), T(0,0)=1, T(1,0)=1, T(1,1)=2, T(n,k)=0 if k<0 or if k>n. - Philippe Deléham, Jan 11 2014
T(n, k) = binomial(2*n-k, k)*hypergeom([1, 1, -k], [1, 1 - 2*k + 2*n], -1). - Peter Luschny, Oct 28 2018

Extensions

Definition and comments corrected by Philippe Deléham, Jan 11 2014
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