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Search: id:A157539
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| A157539 |
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Half the number of length n integer sequences with sum zero and sum of squares 98. |
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+0
1
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| 1, 9, 54, 430, 5265, 51471, 471996, 4601556, 43269345, 363940555, 2806131702, 20371562718, 141703205917, 953199973950, 6225689789880, 39490548010664, 242779946083425, 1445870078850825, 8356848826556090, 46996171775421630
(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,0,98)/2.
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CROSSREFS
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Sequence in context: A037599 A037704 A093847 this_sequence A157546 A157560 A157588
Adjacent sequences: A157536 A157537 A157538 this_sequence A157540 A157541 A157542
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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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