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A157544
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Half the number of length n integer sequences with sum zero and sum of squares 288.
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1
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1, 3, 18, 770, 20805, 522753, 9593507, 138576324, 1907158560, 25880343115, 341234146077, 4348150676532, 53202598238062, 622919366722485, 6980872709154870, 75312434538456228, 787522030868617855
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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LINKS
| R. H. Hardin, Table of n, a(n) for n=2..50
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FORMULA
| [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,0,288)/2.
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CROSSREFS
| Sequence in context: A070953 A163261 A064846 * A202946 A000853 A065402
Adjacent sequences: A157541 A157542 A157543 * A157545 A157546 A157547
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KEYWORD
| nonn
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net) Mar 02 2009
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