|
| |
|
|
A157562
|
|
Half the number of length n integer sequences with sum zero and sum of squares 1800.
|
|
1
|
|
|
|
1, 3, 126, 6510, 336015, 19347993, 928126199, 34039360092, 1173329179500, 39563049010881, 1301454506052525, 41455087636231074, 1268529094022948940, 37131123353064641460, 1040240395936575811890, 28055696919876575091824
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
2,2
|
|
|
LINKS
|
|
|
|
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,0,1800)/2.
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
