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Search: id:A157588
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| A157588 |
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Half the number of length n integer sequences with sum zero and sum of squares 6272. |
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+0
1
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| 1, 9, 54, 18490, 3080025, 281083131, 20455480647, 1378645284663, 90798695826120, 5747081242763245, 353783429708291517, 21210677666294419836, 1217797507802900629878, 66543379957754376544455
(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,0,6272)/2.
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CROSSREFS
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Sequence in context: A157539 A157546 A157560 this_sequence A058849 A058852 A145875
Adjacent sequences: A157585 A157586 A157587 this_sequence A157589 A157590 A157591
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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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