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Search: id:A157594
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| A157594 |
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Half the number of length n integer sequences with sum zero and sum of squares 7688. |
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+0
1
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| 1, 9, 198, 29790, 4026105, 406849401, 33869423679, 2526809359383, 185063876167860, 12982668662313075, 884404700588788401, 58698938381426781945, 3731136219706944217260, 225710021147180429934270
(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,0,7688)/2.
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CROSSREFS
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Sequence in context: A019566 A157563 A003026 this_sequence A064756 A093708 A052145
Adjacent sequences: A157591 A157592 A157593 this_sequence A157595 A157596 A157597
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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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