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Search: id:A157571
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| A157571 |
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Half the number of length n integer sequences with sum zero and sum of squares 3042. |
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+0
1
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| 1, 9, 270, 10990, 622725, 43526469, 2629049500, 142957923228, 7300452572415, 342254197570615, 14695487432860410, 589524950365892190, 22721530823371062501, 851515705898338365990, 31013728074479042288280
(list; graph; listen)
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OFFSET
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2,2
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LINKS
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Ron Hardin, Table of n, a(n) for n=2..50
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FORMULA
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[cache enabling] count(n,s,ss)->count(n,t,tt) where t=s mod n, q=(t-s)/n, tt=ss+2*q*s+n*q^2; count(n,t,tt)=sum[i^2<=tt]{ count(n-1,t-i,tt-i^2) }. a(n)=count(n,0,3042)/2.
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CROSSREFS
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Sequence in context: A081059 A144684 A088672 this_sequence A028456 A119408 A012234
Adjacent sequences: A157568 A157569 A157570 this_sequence A157572 A157573 A157574
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin (rhhardin(AT)att.net) Mar 02 2009
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