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A157579 Half the number of length n integer sequences with sum zero and sum of squares 4418. 1
1, 3, 294, 21630, 1556655, 102426933, 6421722076, 420393758436, 26609856588945, 1503958534048245, 77827209776501394, 3793522397195559678, 177172760525971961023, 8001788984919141620040, 350900981113969220953080 (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,0,4418)/2.

CROSSREFS

Sequence in context: A199644 A124357 A212798 * A104821 A282195 A334177

Adjacent sequences:  A157576 A157577 A157578 * A157580 A157581 A157582

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified October 30 12:22 EDT 2020. Contains 338079 sequences. (Running on oeis4.)