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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A085791 Triangle T(n,k) read by rows; given by [0,1,0,1,0,1,0,1,...] DELTA [1,0,1,1,1,2,1,3,1,4,1,5,...], where DELTA is the operator defined in A084938.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 6, 7, 1, 0, 1, 10, 24, 16, 1, 0, 1, 15, 60, 86, 40, 1, 0, 1, 21, 125, 301, 312, 116, 1, 0, 1, 28, 231, 826, 1443, 1215, 395, 1, 0, 1, 36, 392, 1932, 4992, 7055, 5187, 1551, 1, 0, 1, 45, 624, 4032, 14274, 29629, 36242, 24280
Offset: 0

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Author

Philippe Deléham, Jul 23 2003

Keywords

Examples

			1;
0, 1;
0, 1, 1;
0, 1, 3, 1;
0, 1, 6, 7, 1;
0, 1, 10, 24, 16, 1; ....
		

Crossrefs

Formula

Sum_{k>=0} T(n,k) = A000110(n).
T(n + 1; 2) = A000217(n).
T(n + 2; 3) = A014205(n)= (1/12)*(n + 5)*(n + 1)*n^2.
T(n + 2; n + 1) = A029761(n).

A130749 Triangle A007318*A090181 (as infinite lower triangular matrices) .

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 7, 6, 1, 1, 15, 24, 10, 1, 1, 31, 80, 60, 15, 1, 1, 63, 240, 280, 125, 21, 1, 1, 127, 672, 1120, 770, 231, 28, 1, 1, 255, 1792, 4032, 3920, 1806, 392, 36, 1, 1, 511, 4608, 13440, 17472, 11340, 3780, 624, 45, 1
Offset: 0

Views

Author

Philippe Deléham, Jul 13 2007

Keywords

Examples

			Triangle begins:
  1;
  1,   1;
  1,   3,    1;
  1,   7,    6,     1;
  1,  15,   24,    10,     1;
  1,  31,   80,    60,    15,     1;
  1,  63,  240,   280,   125,    21,    1;
  1, 127,  672,  1120,   770,   231,   28,   1;
  1, 255, 1792,  4032,  3920,  1806,  392,  36,  1;
  1, 511, 4608, 13440, 17472, 11340, 3780, 624, 45,  1;
  ...
		

Crossrefs

Programs

  • Mathematica
    nmax = 9;
    T1[n_, k_] := Binomial[n, k];
    T2[n_, k_] := Sum[(-1)^(j-k) Binomial[2n-j, j] Binomial[j, k] CatalanNumber[n-j], {j, 0, n}];
    T[n_, k_] := Sum[T1[n, m] T2[m, k], {m, 0, n}];
    Table[T[n, k], {n, 0, nmax}, {k, 0, n}] // Flatten (* Jean-François Alcover, Nov 10 2018 *)
  • Maxima
    N(n, k):=(binomial(n, k-1)*binomial(n, k))/n;
    T(n, k):=if k=0 then 1 else sum(binomial(n, i)*N(i, k), i, 1, n); /* Vladimir Kruchinin, Jan 08 2022 */

Formula

Sum_{k=0..n} T(n,k) = A007317(n+1).
G.f.: 1/(1-x-xy/(1-x/(1-x-xy/(1-x/(1-x-xy/(1-x.... (continued fraction); [Paul Barry, Jan 12 2009]
T(n,k) = Sum_{i=1..n} binomial(n, i)*N(i,k), T(n,0)=1, where N(n,k) is the triangle of Narayana numbers A001263. - Vladimir Kruchinin, Jan 08 2022
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