|
|
A157565
|
|
Half the number of length n integer sequences with sum zero and sum of squares 2178.
|
|
1
|
|
|
1, 3, 198, 9310, 376485, 22631679, 1141749532, 52484724372, 2266995222285, 89935056097975, 3267564223225962, 110915350947910158, 3617265650971040159, 114705568549182973950, 3535047653641613917560, 105710505247924746059104
(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,0,2178)/2.
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|