OFFSET
3,3
COMMENTS
A generalized Petersen graph P(n,k) has 2n nodes and 3n edges and consists of an outer n-gon and an inner {n,k} star polygon for some k in the range 1<=k<=floor((n-1)/2); sequence gives number of nonisomorphic generalized Petersen graphs P(n,k) (for any k).
LINKS
Eric Weisstein's World of Mathematics, Generalized Petersen Graph
EXAMPLE
The generalized Petersen graphs P(22,k) for k = 1, 2, 3, 4, 5, 6, 8, 10 are pairwise nonisomorphic, so a(22) = 8. - Arjana Zitnik (Arjana.Zitnik(AT)fmf.uni-lj.si)
MATHEMATICA
CountDistinct /@ Table[CanonicalGraph[PetersenGraph[n, k]], {n, 3, 79}, {k, (n - 1)/2}] (* Eric W. Weisstein, May 13 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Oct 28 2002
EXTENSIONS
My colleague Arjana Zitnik (Arjana.Zitnik(AT)fmf.uni-lj.si) found that a(22) was wrong. - Tomaz Pisanski, Nov 23 2004
Sequence corrected and extended by Eric W. Weisstein, Nov 28 2004
STATUS
approved