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
Programs
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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
Comments