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Search: id:A157559
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| A157559 |
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Half the number of length n integer sequences with sum zero and sum of squares 1458. |
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+0
1
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| 1, 3, 162, 5470, 204405, 10044237, 418371436, 15735232164, 556455670755, 18061671242945, 536877862194894, 14910514196745102, 397858116730316515, 10322446421549098305, 260281325962170069480, 6368185576937692717552
(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,0,1458)/2.
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CROSSREFS
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Sequence in context: A108159 A067322 A157440 this_sequence A157586 A042439 A030258
Adjacent sequences: A157556 A157557 A157558 this_sequence A157560 A157561 A157562
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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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