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A157572
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Half the number of length n integer sequences with sum zero and sum of squares 3200.
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1
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1, 3, 42, 13330, 1149525, 68923281, 3762973571, 184036492377, 8678968080840, 390210773279547, 17118756925603575, 733096379424490302, 30076017737894907870, 1173815703627064565445, 43806372065182513944702
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OFFSET
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2,2
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LINKS
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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,0,3200)/2.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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