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Search: id:A157599
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| A157599 |
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Half the number of length n integer sequences with sum zero and sum of squares 8978. |
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+0
1
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| 1, 9, 402, 44230, 4512465, 423267831, 37803628716, 3527887213476, 318332583745245, 25647872392849575, 1892012326768856754, 131465592083214083058, 8752726227773492626389, 563521423775802944905950
(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,0,8978)/2.
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CROSSREFS
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Sequence in context: A124042 A012191 A012078 this_sequence A063876 A063156 A058850
Adjacent sequences: A157596 A157597 A157598 this_sequence A157600 A157601 A157602
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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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