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Search: id:A157585
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| A157585 |
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Half the number of length n integer sequences with sum zero and sum of squares 5618. |
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+0
1
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| 1, 3, 330, 27570, 2233965, 165759111, 11709395180, 864416336904, 61700500723635, 3932420281395045, 229474040212588578, 12613127103936869874, 664285970637825836755, 33831654295810674426165, 1673010760008675643666440
(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,0,5618)/2.
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CROSSREFS
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Sequence in context: A080976 A160070 A112895 this_sequence A045645 A005335 A057121
Adjacent sequences: A157582 A157583 A157584 this_sequence A157586 A157587 A157588
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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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