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 1-3 of 3 results.

A098512 Second column and subdiagonal of number triangle A098509.

Original entry on oeis.org

1, 1, 1, 5, 7, 42, 22, 429, 715, 4862, 8398, 58786, 52003, 742900, 1337220, 646323, 17678835, 129644790, 79606450, 1767263190, 328206021, 8155422340, 45741281820, 343059613650, 107492012277, 4861946401452, 9183676536076
Offset: 0

Views

Author

Paul Barry, Sep 11 2004

Keywords

Crossrefs

Programs

  • Maple
    C := n -> binomial(2*n,n)/(n+1):
    A098512 := n -> C(n)/igcd(n,C(n)): # Peter Luschny, Oct 06 2011

Formula

a(n) = denominator(n(n+1)/binomial(2n, n)).
a(n) = denominator(n/C(n)). - Paul Barry, Nov 17 2004
a(n) = C(n) / gcd(n, C(n)). - Peter Luschny, Oct 06 2011

A098510 Row sums of a matrix associated to the inverse of a Catalan scaled binomial matrix.

Original entry on oeis.org

1, 2, 5, 20, 49, 210, 429, 2860, 7293, 34034, 113373, 537472, 1359507, 6611810, 24627135, 37917616, 177181213, 973514514, 1647439975, 12026570280, 17818756259, 98555142278, 502860886675, 4577646742140, 6402665244089
Offset: 0

Views

Author

Paul Barry, Sep 11 2004

Keywords

Comments

Row sums of A098509.

Formula

a(n)=sum{k=0..n, denominator((n+1)binomial(n, k)/binomial(2n, n))}

A098511 Diagonal sums of a matrix associated to the inverse of a Catalan scaled binomial matrix.

Original entry on oeis.org

1, 1, 3, 6, 21, 54, 186, 479, 1938, 5795, 22888, 70781, 286443, 861463, 3592105, 11492256, 39274353, 148852401, 613876868, 1917516257, 8511689170, 25445125513, 100975365920, 390096404027, 1666653892303, 5319341488465
Offset: 0

Views

Author

Paul Barry, Sep 11 2004

Keywords

Comments

Diagonal sums of A098509.

Formula

a(n)=sum{k=0..floor(n/2), denominator((n-k+1)Binomial(n-k, k)/Binomial(2(n-k), n-k))}
Showing 1-3 of 3 results.