login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A157568
Half the number of length n integer sequences with sum zero and sum of squares 2592.
1
1, 3, 54, 6710, 552975, 42285705, 2331601391, 101037868356, 4170874974720, 169800684016755, 6716524310262195, 256753303252023825, 9424676123728329646, 331044899193112524525, 11129765080736905244370, 360217055543666912443944
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,0,2592)/2.
CROSSREFS
Sequence in context: A158103 A174579 A171739 * A156911 A214006 A154604
KEYWORD
nonn
AUTHOR
R. H. Hardin Mar 02 2009
STATUS
approved