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

0,4

Links

Table of n, a(n) for n=0..26.

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

Maple

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

Crossrefs

Cf. A093526, A093527, A000108.

Sequence in context: A178342 A117751 A093526 * A234040 A292010 A064082

Adjacent sequences: A098509 A098510 A098511 * A098513 A098514 A098515

Keyword

easy,nonn

Author

Paul Barry, Sep 11 2004

Status

approved