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Search: id:A157564
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| A157564 |
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Half the number of length n integer sequences with sum zero and sum of squares 2048. |
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+0
1
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| 1, 3, 6, 6830, 561735, 29360121, 1242596383, 47858305311, 1805644314360, 65361758855305, 2298374956416891, 78740814179665443, 2583344854373884146, 80658838456091971635, 2408249945284962451650, 69283128843699421305698
(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,0,2048)/2.
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CROSSREFS
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Sequence in context: A071106 A157548 A134901 this_sequence A122182 A157596 A111316
Adjacent sequences: A157561 A157562 A157563 this_sequence A157565 A157566 A157567
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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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