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Search: id:A157602
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| A157602 |
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Half the number of length n integer sequences with sum zero and sum of squares 9800. |
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+0
1
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| 1, 9, 378, 39990, 6207435, 649615491, 61839617931, 5291171373321, 436429418237100, 34318546032095787, 2635382197485052125, 197482663359487272702, 14177933118661639661880, 968391907322785974064260
(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,0,9800)/2.
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CROSSREFS
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Sequence in context: A051848 A157567 A157593 this_sequence A124042 A012191 A012078
Adjacent sequences: A157599 A157600 A157601 this_sequence A157603 A157604 A157605
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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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