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Search: id:A157578
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| A157578 |
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Half the number of length n integer sequences with sum zero and sum of squares 4232. |
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+0
1
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| 1, 3, 150, 15210, 1639575, 123643611, 7614820759, 421492526271, 22902703731540, 1192049263269315, 60248523072916695, 2966823784716819963, 139916416171825355244, 6279781745619795030660, 269526833541639073889370
(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,0,4232)/2.
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CROSSREFS
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Sequence in context: A118840 A111816 A157555 this_sequence A137802 A100203 A095225
Adjacent sequences: A157575 A157576 A157577 this_sequence A157579 A157580 A157581
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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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