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A157577 Half the number of length n integer sequences with sum zero and sum of squares 4050. 1
1, 3, 378, 18910, 992325, 74527005, 5338966892, 339980231676, 20037272191665, 1077068920503015, 53256851208061050, 2465137614876120834, 109671118311748056245, 4742369931941953806600, 199288535032516918383432 (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,0,4050)/2.

CROSSREFS

Sequence in context: A110717 A068988 A136025 * A062604 A160192 A304424

Adjacent sequences:  A157574 A157575 A157576 * A157578 A157579 A157580

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.)