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A366119
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Expansion of (1/x) * Series_Reversion( x*(1+x+x^3)/(1+x)^5 ).
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4
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1, 4, 22, 139, 950, 6831, 50899, 389402, 3040433, 24127641, 194015198, 1577355740, 12943616840, 107061667210, 891666351501, 7471125565836, 62932782325745, 532621542290355, 4526846632642489, 38621126867786485, 330635368752515710, 2839444812305017875
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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/3)} (-1)^k * binomial(n+k,k) * binomial(4*n-k+4,n-3*k).
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PROG
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(PARI) a(n) = sum(k=0, n\3, (-1)^k*binomial(n+k, k)*binomial(4*n-k+4, n-3*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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