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Search: id:A157554
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| A157554 |
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Half the number of length n integer sequences with sum zero and sum of squares 968. |
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+0
1
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| 1, 3, 66, 3990, 178335, 6510483, 190667659, 5047394427, 131071431060, 3262733109790, 78872812374741, 1857536871457917, 41896936373100900, 899337065318075790, 18460566561637223550, 365127965985604164628
(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,0,968)/2.
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CROSSREFS
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Sequence in context: A003359 A157543 A157984 this_sequence A165655 A157576 A105443
Adjacent sequences: A157551 A157552 A157553 this_sequence A157555 A157556 A157557
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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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