OFFSET
1,2
LINKS
M. Baake and R. V. Moody, Similarity submodules and root systems in four dimensions, Canad. J. Math. 51 (1999), 1258-1276.
FORMULA
a(n) = Sum_{k=1..n} A035185(k);
a(n) is asymptotic to c*n where c = log(1+sqrt(2))/sqrt(2) = 0.62322524014023051339402008...
a(n) = Sum_{k=1..n} K(k,2)*floor(n/k) where K(x,y) is the Kronecker symbol. - Benoit Cloitre, Oct 31 2009
MATHEMATICA
Table[DivisorSum[n, KroneckerSymbol[2, #]&], {n, 1, 100}] // Accumulate (* Jean-François Alcover, Nov 11 2018 *)
PROG
(PARI) a(n)=sum(k=1, n, kronecker(k, 2)*floor(n/k)) \\ Benoit Cloitre, Oct 31 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Dec 31 2002
EXTENSIONS
Corrected by T. D. Noe, Nov 02 2006
STATUS
approved