OFFSET
1,1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
J. S. Rutherford, Generating functions for the cage isomers of the C_{20n} icosahedral fullerenes, J. Mathematical Chem., 14 (1993), 385-390. See Eq. (3).
J. S. Rutherford, The enumeration and symmetry-significant properties of derivative lattices, Act. Cryst. A48 (1992), 500-508. [See Sect. (7), p. 505.]
FORMULA
a(n) = A195198(n) for n >= 1.
a(n) = Sum_{ m: m^2|n } A154272(n/m^2). - Andrey Zabolotskiy, May 07 2018
MATHEMATICA
Array[Boole@ OddQ@ If[# < 1, 0, DivisorSum[#, KroneckerSymbol[-3, #] &]] &, 105] (* Michael De Vlieger, Nov 05 2017, after Michael Somos at A002324 *)
PROG
(PARI)
A002324(n) = if( n<1, 0, sumdiv(n, d, (d%3==1) - (d%3==2)));
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
N. J. A. Sloane, Mar 12 2009
EXTENSIONS
More terms from Antti Karttunen, Nov 05 2017
STATUS
approved