OFFSET
0,7
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = Sum_{k=0..floor(n/2)} binomial(L(k/3), n-2k), where L(j/p) is the Legendre symbol of j and p.
MATHEMATICA
Table[Sum[Binomial[JacobiSymbol[k, 3], n-2*k], {k, 0, Floor[n/2]}], {n, 0, 80}] (* G. C. Greubel, Jun 02 2021 *)
PROG
(Sage) [sum( binomial(kronecker(k, 3), n-2*k) for k in (0..n//2) ) for n in (0..80)] # G. C. Greubel, Jun 02 2021
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paul Barry, Mar 16 2006
STATUS
approved