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Search: id:A157558
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| A157558 |
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Half the number of length n integer sequences with sum zero and sum of squares 1352. |
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+0
1
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| 1, 9, 90, 4710, 294975, 12521313, 439040875, 13748247801, 422094067740, 12416563759270, 354721205123505, 9872974834469253, 263171856408106464, 6676220201317388190, 161958493217535635430, 3785772107967822217382
(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,0,1352)/2.
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CROSSREFS
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Sequence in context: A062815 A160569 A157545 this_sequence A157584 A128384 A077334
Adjacent sequences: A157555 A157556 A157557 this_sequence A157559 A157560 A157561
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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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