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A157565
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Half the number of length n integer sequences with sum zero and sum of squares 2178.
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1
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1, 3, 198, 9310, 376485, 22631679, 1141749532, 52484724372, 2266995222285, 89935056097975, 3267564223225962, 110915350947910158, 3617265650971040159, 114705568549182973950, 3535047653641613917560, 105710505247924746059104
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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LINKS
| R. H. Hardin, Table of n, a(n) for n=2..50
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FORMULA
| [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,0,2178)/2.
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CROSSREFS
| Sequence in context: A093978 A101382 A000724 * A157598 A023310 A054701
Adjacent sequences: A157562 A157563 A157564 * A157566 A157567 A157568
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KEYWORD
| nonn
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net) Mar 02 2009
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