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A157581 Half the number of length n integer sequences with sum zero and sum of squares 4802. 1
1, 15, 390, 21010, 1806015, 123582921, 7932838172, 541388995092, 35637846633315, 2098170095389555, 113237331813959034, 5754386605886291022, 280189305372079613419, 13193562175797681608910, 603200922513642478421880 (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,0,4802)/2.

CROSSREFS

Sequence in context: A129615 A286139 A069990 * A143001 A250950 A323838

Adjacent sequences:  A157578 A157579 A157580 * A157582 A157583 A157584

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 02 2009

STATUS

approved

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Last modified January 24 04:47 EST 2022. Contains 350534 sequences. (Running on oeis4.)