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A157590 Half the number of length n integer sequences with sum zero and sum of squares 6728. 1
1, 3, 186, 26130, 3296565, 312282243, 24263695547, 1693530847881, 116031418602660, 7614709044887230, 485263665372726339, 30129597082995141381, 1791597506670518058876, 101387984322685789268190 (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,0,6728)/2.

CROSSREFS

Sequence in context: A203562 A198701 A157561 * A157236 A058856 A158469

Adjacent sequences:  A157587 A157588 A157589 * A157591 A157592 A157593

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified July 4 17:09 EDT 2022. Contains 355081 sequences. (Running on oeis4.)