OFFSET
1,7
FORMULA
Despite the definition, a(n) has an unexpectedly simple asymptotic behavior h: a(n)=(n/4)^2 +O(n) and more precisely it appears that : (n/4)^2-n/8 <= a(n) < (n/4)^2+n/2 with equality (on left side) for infinitely many values of n.
PROG
(PARI) a(n)=sum(k=1, n, k%sum(i=0, k-1, 1-subst(Pol(binary(i)), x, 1)%2))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, May 27 2003
STATUS
approved