A185278 - OEIS

%I #19 Sep 06 2018 14:55:02

%S 1,1,2,1,2,2,2,2,3,2,4,2,3,3,5,2,5,3,4,3,6,4,6,4,5,4,8,3,8,5,6,5,7,4,

%T 10,5,7,6,11,4,11,6,7,6,12,6,11,6,9,7,14,5,11,8,10,8,15,6,16,8,10,9,

%U 14,6,17,9,12,7,18,8,19,10,11,10,16,7,20,10,14,11,21,8,18,11,15,12,23,7,19,12,16,12,19,10,25,11,16,11

%N Number of isomorphism classes of generalized Petersen graphs G(n,k) on 2n vertices with gcd(n,k) = 1.

%H Robert Israel, <a href="/A185278/b185278.txt">Table of n, a(n) for n = 3..10000</a>

%H Marko Petkovsek and Helena Zakrajsek, <a href="http://amc-journal.eu/index.php/amc/article/view/113">Enumeration of I-graphs: Burnside does it again</a>, Ars Mathematica Contemporanea, 2 (2009) 241-262.

%H A. Steimle and W. Staton, <a href="http://dx.doi.org/10.1016/j.disc.2007.12.074">The isomorphism classes of the generalized Petersen graphs</a>, Discrete Math. 309 (2009), 231-237.

%F a(n) = (A000010(n) + A060594(n) + A000089(n))/4.

%p # using functions A060594 and A000089 as defined in those sequences

%p f:= n -> (numtheory:-phi(n)+A060594(n)+A000089(n))/4:

%p map(f, [$3..100]); # _Robert Israel_, Sep 06 2018

%Y Cf. A000010, A000089, A060594.

%K nonn,look

%O 3,3

%A _N. J. A. Sloane_, Feb 19 2011