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A157580 Half the number of length n integer sequences with sum zero and sum of squares 4608. 1
1, 3, 18, 11970, 1334085, 133955073, 9824277155, 567625941444, 31246085767560, 1696086845812315, 89452573267087437, 4559354532659814420, 223147765159835078290, 10450853058701142231795, 468478402281324084911670 (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,0,4608)/2.

CROSSREFS

Sequence in context: A057133 A321249 A001999 * A101293 A227882 A189799

Adjacent sequences:  A157577 A157578 A157579 * A157581 A157582 A157583

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified August 22 07:17 EDT 2019. Contains 326172 sequences. (Running on oeis4.)