|
| |
|
|
A157546
|
|
Half the number of length n integer sequences with sum zero and sum of squares 392.
|
|
1
| |
|
|
1, 9, 54, 1290, 47385, 1080891, 19941831, 335927439, 5541820740, 87714576070, 1349748111657, 20228679068676, 290345411571852, 3966279413712840, 51810189395306490, 652108043960695984, 7955418278826810531
(list; graph; refs; listen; history; 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,0,392)/2.
|
|
|
CROSSREFS
| Sequence in context: A093847 A157539 A205814 * A157560 A157588 A058849
Adjacent sequences: A157543 A157544 A157545 * A157547 A157548 A157549
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| R. H. Hardin (rhhardin(AT)att.net) Mar 02 2009
|
| |
|
|
