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Search: id:A157570
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| A157570 |
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Half the number of length n integer sequences with sum zero and sum of squares 2888. |
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+0
1
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| 1, 9, 114, 11430, 928665, 57312801, 2929653363, 133959064275, 6012597282660, 258520740868390, 10793900036914731, 439085564014381089, 17106142080255638592, 634240156516816014270, 22487281301691416873070
(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,0,2888)/2.
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CROSSREFS
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Sequence in context: A165224 A012116 A157551 this_sequence A157233 A083305 A092913
Adjacent sequences: A157567 A157568 A157569 this_sequence A157571 A157572 A157573
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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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