



1, 2, 2, 3, 3, 3, 5, 6, 7, 7, 7, 7, 7, 9, 9, 10, 12, 13, 13, 13, 13, 13, 15, 15, 16, 16, 16, 18, 18, 18, 20, 21, 21, 23, 23, 24, 24, 24, 24, 24, 26, 26, 26, 26, 26, 28, 30, 30, 33, 34, 34, 34, 34, 34, 34, 36, 36, 36, 36, 36, 36, 38, 40, 41, 41, 41, 41, 43, 43, 43, 45, 46, 48, 48
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..74.
M. Baake and R. V. Moody, Similarity submodules and root systems in four dimensions, Canad. J. Math. 51 (1999), 12581276.


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 (* JeanFrançois Alcover, Nov 11 2018 *)


PROG

(PARI) a(n)=sum(k=1, n, kronecker(k, 2)*floor(n/k)) \\ Benoit Cloitre, Oct 31 2009


CROSSREFS

Cf. A035185, A078428.
Sequence in context: A240519 A318037 A326165 * A239518 A293924 A307730
Adjacent sequences: A078459 A078460 A078461 * A078463 A078464 A078465


KEYWORD

nonn


AUTHOR

Benoit Cloitre, Dec 31 2002


EXTENSIONS

Corrected by T. D. Noe, Nov 02 2006


STATUS

approved



