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Search: id:A091593
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| 1, -1, -1, 5, -3, -21, 51, 41, -391, 407, 1927, -6227, -2507, 49347, -71109, -236079, 966129, 9519, -7408497, 13685205, 32079981, -167077221, 60639939, 1209248505, -2761755543, -4457338681, 30629783831, -22124857219, -206064020315, 572040039283, 590258340811
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Hankel transform is (-2)^C(n+1,2). [From Paul Barry (pbarry(AT)wit.ie), Apr 28 2009]
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LINKS
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Index entries for reversions of series
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FORMULA
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G.f.: (-(1+x)+sqrt(1+2x+9x^2))/(4x)
a(n)=sum{k=0..floor(n/2), binomial(n, 2k)*C(k)*(-1)^(n-k)2^k}, where C(n) is A000108. - Paul Barry (pbarry(AT)wit.ie), May 16 2005
G.f.: 1/(1+x+2x^2/(1+x+2x^2/(1+x+2x^2/(1+x+2x^2/(1+ ... (continued fraction). [From Paul Barry (pbarry(AT)wit.ie), Apr 28 2009]
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CROSSREFS
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Sequence in context: A099730 A072800 A154825 this_sequence A139699 A069607 A128366
Adjacent sequences: A091590 A091591 A091592 this_sequence A091594 A091595 A091596
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Jan 23 2004
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