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A157566
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Half the number of length n integer sequences with sum zero and sum of squares 2312.
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1
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1, 3, 102, 8190, 665685, 36705753, 1679350127, 68733531189, 2760184991340, 106183264044550, 3966764429800029, 144378604643078598, 5032695166253713140, 166954292511159130110, 5296343179095984782250, 161894623559389026065130
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OFFSET
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2,2
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LINKS
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R. H. 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,0,2312)/2.
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CROSSREFS
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Sequence in context: A290027 A224817 A157549 * A157600 A139908 A128070
Adjacent sequences: A157563 A157564 A157565 * A157567 A157568 A157569
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KEYWORD
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nonn
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AUTHOR
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R. H. Hardin Mar 02 2009
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STATUS
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approved
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