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A157547
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Half the number of length n integer sequences with sum zero and sum of squares 450.
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1
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1, 3, 126, 2170, 37335, 921333, 21967484, 466292604, 9161931075, 164162481681, 2705726857350, 41747317681290, 619096670144225, 8923605271290360, 124998845674120920, 1699006653803990456, 22382667992161145863
(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,0,450)/2.
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CROSSREFS
| Sequence in context: A085531 A130614 A114877 * A160879 A157562 A157592
Adjacent sequences: A157544 A157545 A157546 * A157548 A157549 A157550
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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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