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Search: id:A157557
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| A157557 |
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Half the number of length n integer sequences with sum zero and sum of squares 1250. |
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+0
1
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| 1, 3, 222, 7810, 245715, 7887621, 271336828, 9598223664, 323149486005, 9653120522639, 265199107509930, 6875831133411318, 170878889034103705, 4105071237469192095, 95749849725794169816, 2169082695217727013712
(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,0,1250)/2.
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CROSSREFS
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Sequence in context: A063836 A140441 A071881 this_sequence A157582 A131493 A099426
Adjacent sequences: A157554 A157555 A157556 this_sequence A157558 A157559 A157560
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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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