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A369158
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Expansion of (1/x) * Series_Reversion( x / ((1+x)^2+x^4) ).
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3
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1, 2, 5, 14, 43, 142, 495, 1794, 6686, 25436, 98311, 384826, 1522283, 6075838, 24437937, 98956270, 403080170, 1650502292, 6790018182, 28050896964, 116322826479, 484029536374, 2020386475025, 8457397801150, 35495812337114, 149336478356692, 629685490668799
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = (1/(n+1)) * Sum_{k=0..floor(n/4)} binomial(n+1,k) * binomial(2*n-2*k+2,n-4*k).
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PROG
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(PARI) my(N=30, x='x+O('x^N)); Vec(serreverse(x/((1+x)^2+x^4))/x)
(PARI) a(n) = sum(k=0, n\4, binomial(n+1, k)*binomial(2*n-2*k+2, n-4*k))/(n+1);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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