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A157575 Half the number of length n integer sequences with sum zero and sum of squares 3698. 1
1, 9, 258, 18070, 1193265, 71833671, 4116288204, 246535687044, 14276990551185, 738244819092055, 34951581964536930, 1558650106287998802, 66599892238284898857, 2751910251508099981950, 110408459890796284831080 (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,0,3698)/2.

CROSSREFS

Sequence in context: A183493 A183424 A160073 * A072158 A001823 A229259

Adjacent sequences:  A157572 A157573 A157574 * A157576 A157577 A157578

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified May 24 18:34 EDT 2019. Contains 323534 sequences. (Running on oeis4.)