A098512 Second column and subdiagonal of number triangle A098509.

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

Author

Paul Barry, Sep 11 2004

Keywords

• easy
• nonn

Crossrefs

Cf. A093526, A093527, A000108.

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