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Search: id:A157582
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| A157582 |
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Half the number of length n integer sequences with sum zero and sum of squares 5000. |
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+0
1
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| 1, 3, 222, 23430, 2211435, 165640041, 11463980983, 700674124347, 41384377023300, 2326405435793384, 127560765651968055, 6827700441824422953, 350130844722624976920, 17081201454932094454170, 796830250007891403178002
(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,0,5000)/2.
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CROSSREFS
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Sequence in context: A140441 A071881 A157557 this_sequence A131493 A099426 A100201
Adjacent sequences: A157579 A157580 A157581 this_sequence A157583 A157584 A157585
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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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