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Search: id:A157584
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| A157584 |
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Half the number of length n integer sequences with sum zero and sum of squares 5408. |
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+0
1
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| 1, 9, 90, 17270, 2392575, 203322273, 14072688875, 881578169937, 54028224275760, 3177868465756435, 181594395820598805, 10109617693345774539, 538976083520642296074, 27345902242485061861185, 1326768997661185039512750
(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,0,5408)/2.
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CROSSREFS
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Sequence in context: A160569 A157545 A157558 this_sequence A128384 A077334 A020243
Adjacent sequences: A157581 A157582 A157583 this_sequence A157585 A157586 A157587
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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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