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Search: id:A157575
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| A157575 |
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Half the number of length n integer sequences with sum zero and sum of squares 3698. |
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+0
1
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| 1, 9, 258, 18070, 1193265, 71833671, 4116288204, 246535687044, 14276990551185, 738244819092055, 34951581964536930, 1558650106287998802, 66599892238284898857, 2751910251508099981950, 110408459890796284831080
(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,0,3698)/2.
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CROSSREFS
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Sequence in context: A135484 A025133 A160073 this_sequence A072158 A001823 A117796
Adjacent sequences: A157572 A157573 A157574 this_sequence A157576 A157577 A157578
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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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