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A157572 Half the number of length n integer sequences with sum zero and sum of squares 3200. 1
1, 3, 42, 13330, 1149525, 68923281, 3762973571, 184036492377, 8678968080840, 390210773279547, 17118756925603575, 733096379424490302, 30076017737894907870, 1173815703627064565445, 43806372065182513944702 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

R. H. Hardin, Table of n, a(n) for n=2..50

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,0,3200)/2.

CROSSREFS

Sequence in context: A157552 A058808 A155210 * A332973 A137192 A253577

Adjacent sequences:  A157569 A157570 A157571 * A157573 A157574 A157575

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified October 27 09:08 EDT 2020. Contains 338035 sequences. (Running on oeis4.)