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A157567 Half the number of length n integer sequences with sum zero and sum of squares 2450. 1
1, 9, 378, 13330, 689715, 30934071, 1463659596, 72481823352, 3407856306435, 142400570465307, 5478965101306950, 198874787418398598, 6919440283487706065, 232730571288134765160, 7599816260357477794632, 241028324482889751669040 (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,0,2450)/2.

CROSSREFS

Sequence in context: A238561 A290574 A218714 * A157593 A157602 A124042

Adjacent sequences:  A157564 A157565 A157566 * A157568 A157569 A157570

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified October 27 22:56 EDT 2020. Contains 338044 sequences. (Running on oeis4.)