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A098512
Second column and subdiagonal of number triangle A098509.
3
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
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
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Sep 11 2004
STATUS
approved