A157563 Half the number of length n integer sequences with sum zero and sum of squares 1922.

1, 9, 198, 9930, 447345, 19373781, 801643164, 34613610228, 1445069106945, 53870000270295, 1838679236576886, 59112727361906010, 1820954720583759943, 54244177130219463765, 1568969312068377795960, 44074283494841644862536

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,0,1922)/2.

Crossrefs

Sequence in context: A110807 A019566 A338226 * A003026 A157594 A232276

Adjacent sequences: A157560 A157561 A157562 * A157564 A157565 A157566

Keyword

nonn

Author

R. H. Hardin Mar 02 2009

Status

approved