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Search: id:A038112
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| 1, 2, 9, 40, 190, 924, 4578, 22968, 116325, 593450, 3045185, 15699840, 81260816, 421993040, 2197653240, 11472991008, 60023749566, 314621200260, 1651883008050, 8685998428800, 45734484854520, 241098942106440
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n):=sum{k=0..n, C(n+k,k)C(k,n-k)}; - Paul Barry (pbarry(AT)wit.ie), May 13 2006
a(n) = sum(binomial(2*j,n)*(binomial(n+j,2*j)),j=0..n). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 22 2006
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MAPLE
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a:=n->sum(binomial(2*j, n)*(binomial(n+j, 2*j)), j=0..n): seq(a(n), n=0..21); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 22 2006
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PROGRAM
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(PARI) a(n)=if(n<0, 0, sum(k=0, n\2, (2*n-k)!/k!/(n-2*k)!)/n!) (from Michael Somos)
(PARI) a(n)=if(n<0, 0, n++; n*polcoeff(serreverse(x-x^2-x^3+x*O(x^n)), n)) (from Michael Somos)
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CROSSREFS
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a(n)=(n+1)A001002(n+1).
Sequence in context: A020728 A107979 A021001 this_sequence A052512 A166554 A038156
Adjacent sequences: A038109 A038110 A038111 this_sequence A038113 A038114 A038115
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KEYWORD
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nonn
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AUTHOR
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Floor van Lamoen (fvlamoen(AT)hotmail.com)
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