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Search: id:A004130
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| A004130 |
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Numerators in expansion of (1-x)^{-1/4}. |
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+0
4
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| 1, 1, 5, 15, 195, 663, 4641, 16575, 480675, 1762475, 13042315, 48612265, 729183975, 2748462675, 20809788825, 79077197535, 4823709049635, 18443593425075, 141400882925575, 543277076503525, 8366466978154285, 32270658344309385
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Numerators in expansion of sqrt(1/sqrt(1-4x)). - Paul Barry (pbarry(AT)wit.ie), Jul 12 2005
Denominators are in A088802. - Michael Somos Aug 23 2007
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FORMULA
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a(n) = prod(k=1, n, (4k-3)/k * 2^A007814(k)), proved by Mitch Harris, following a conjecture by R. Stephan.
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PROGRAM
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(PARI) {a(n) = if( n<0, 0, numerator( polcoeff( (1 - x +x*O(x^n))^(-1/4), n ) ) ) } /* Michael Somos Aug 23 2007 */
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CROSSREFS
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Cf. A004134.
Cf. A004981, A034255, A034385, A048882.
Cf. A007696, A000265, A049606.
Sequence in context: A034980 A143048 A120602 this_sequence A088869 A134715 A053918
Adjacent sequences: A004127 A004128 A004129 this_sequence A004131 A004132 A004133
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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