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A098512
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Second column and sub-diagonal of number triangle A098509.
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3
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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
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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FORMULA
| a(n)=denominator(n(n+1)/binomial(2n, n))
a(n)=denominator(n/C(n)) - Paul Barry (pbarry(AT)wit.ie), Nov 17 2004
a(n)= C(n) / gcd(n,C(n)) - Peter Luschny, Oct 06 2011
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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
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CROSSREFS
| Cf. A093526, A093527, A000108.
Sequence in context: A178342 A117751 A093526 * A064082 A090520 A066219
Adjacent sequences: A098509 A098510 A098511 * A098513 A098514 A098515
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Sep 11 2004
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