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A105865
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Expansion of (1/(1-2x^2))c(x/(1-2x^2)), where c(x) is the g.f. of A000108.
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0
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1, 1, 4, 9, 30, 94, 328, 1165, 4294, 16134, 61752, 239610, 940716, 3729324, 14908176, 60026109, 243211206, 990897478, 4057013080, 16683617326, 68879236036, 285388549188, 1186296731376, 4945790840338, 20675513743900, 86648395759516
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| G.f.: (1-sqrt((1-4x-2x^2)/(1-2x^2)))/(2x);
a(n)=sum{k=0..floor(n/2), 2^k*C(n-k, k)C(n-2k)}.
Conjecture: (n+1)*a(n) +2(1-2n)*a(n-1) +4*(1-n)*a(n-2) +4*(2n-3)*a(n-3) +4*(n-3)*a(n-4)=0. - R. J. Mathar, Dec 13 2011
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CROSSREFS
| Sequence in context: A151270 A149113 A149114 * A187983 A069103 A041137
Adjacent sequences: A105862 A105863 A105864 * A105866 A105867 A105868
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Apr 23 2005
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