OFFSET
0,2
COMMENTS
a(3n)=a(3n+1)/a(1)=a(3n+2)/a(2); a(9n)=a(9n+3)/a(3)=a(9n+6)/a(6); a(27n)=a(27n+9)/a(9)=a(27n+18)/a(18); a(3^k*n)=a(3^k*n+3^(k-1))/a(3^(k-1))=a(3^k*n+2*3^(k-1))/a(2*3^(k-1)), k>0.
FORMULA
a(n)=sum{k=0..n, L(C(n,k)/3)*3^k} where L(j/p) is the Legendre symbol of j and p.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Apr 06 2006
STATUS
approved