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.

Showing 1-2 of 2 results.

A065432 Triangle related to Catalan triangle: recurrence related to A033877 (Schroeder numbers).

Original entry on oeis.org

1, 1, -1, 1, -2, 0, 1, -3, 1, 1, 1, -4, 3, 2, 0, 1, -5, 6, 2, -2, -2, 1, -6, 10, 0, -6, -4, 0, 1, -7, 15, -5, -11, -3, 5, 5, 1, -8, 21, -14, -15, 4, 15, 10, 0, 1, -9, 28, -28, -15, 19, 26, 6, -14, -14, 1, -10, 36, -48, -7, 42, 30, -16, -42, -28, 0, 1, -11, 45, -75, 14, 70, 16, -60, -70, -14, 42, 42, 1, -12, 55, -110, 54, 96, -28, -120, -70, 56, 126, 84, 0
Offset: 0

Views

Author

Wouter Meeussen, Nov 16 2001

Keywords

Comments

Sums of odd rows are 0, of even rows are the Catalan numbers (A000108) with alternating signs. Row sums of unsigned version give A065441.

Examples

			Triangle starts:
[0] 1;
[1] 1, -1;
[2] 1, -2,  0;
[3] 1, -3,  1,   1;
[4] 1, -4,  3,   2,   0;
[5] 1, -5,  6,   2,  -2, -2;
[6] 1, -6, 10,   0,  -6, -4,  0;
[7] 1, -7, 15,  -5, -11, -3,  5,  5;
[8] 1, -8, 21, -14, -15,  4, 15, 10,   0;
[9] 1, -9, 28, -28, -15, 19, 26,  6, -14, -14.
		

Programs

  • Mathematica
    a[0, 0] := 1; a[n_, k_] := 0/;(k > n||n < 0||k < 0); a[n_, k_] := a[n, k] = a[n, k-1]-2a[n-1, k-1]+a[n-1, k]; Table[a[n, k], {n, 0, 16}, {k, 0, n}]

Extensions

More terms from Sean A. Irvine, Sep 03 2023

A094184 Triangle read by rows in which each term equals the entry above minus the entry left plus twice the entry left-above.

Original entry on oeis.org

1, 1, 1, 1, 2, 0, 1, 3, 1, -1, 1, 4, 3, -2, 0, 1, 5, 6, -2, -2, 2, 1, 6, 10, 0, -6, 4, 0, 1, 7, 15, 5, -11, 3, 5, -5, 1, 8, 21, 14, -15, -4, 15, -10, 0, 1, 9, 28, 28, -15, -19, 26, -6, -14, 14, 1, 10, 36, 48, -7, -42, 30, 16, -42, 28, 0, 1, 11, 45, 75, 14, -70, 16, 60, -70, 14, 42, -42, 1, 12, 55, 110, 54, -96, -28, 120, -70, -56, 126, -84, 0, 1
Offset: 0

Views

Author

Wouter Meeussen, May 06 2004

Keywords

Comments

Row sums are A086990 or A090412. (Superseeker finds that the j-th coefficient of OGF(A090412)(z)*(1-z)^j equals A049122). Same absolute values as A065432. Even rows end in 0, odd rows end in Catalan numbers (A000118) with alternating sign.

Examples

			Table starts {1},{1,1},{1,2,0},{1,3,1,-1},{1,4,3,-2,0},{1,5,6,-2,-2,2}
		

Crossrefs

Programs

Formula

T(i, j)=T(i-1, j)-T(i, j-1)+2*T(i-1, j-1), with T(i, 0)=1 and T(i, j)=0 if j>i.
Showing 1-2 of 2 results.