OFFSET
1,2
COMMENTS
It would appear that a(n)=2^m-1 if 2n+1 is prime.
FORMULA
a(n)=sum{k=0..n, abs(Jacobi(n-k, 2k+1))2^k}
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jul 20 2005
STATUS
approved