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A157574 Half the number of length n integer sequences with sum zero and sum of squares 3528. 1
1, 9, 162, 9030, 900315, 78905043, 5045283243, 254993728356, 12275288985060, 582690164112595, 26896406705910159, 1199420057394958074, 51363567523493108520, 2104956036291257002350, 82564460378872392399390 (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,0,3528)/2.

CROSSREFS

Sequence in context: A237024 A156273 A051232 * A077280 A297436 A041147

Adjacent sequences:  A157571 A157572 A157573 * A157575 A157576 A157577

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified October 20 05:51 EDT 2020. Contains 337897 sequences. (Running on oeis4.)