The OEIS is supported by the many generous donors to the OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A266478 Number of n-vertex simple graphs G_n for which n divides the number of labeled copies of G_n. 1
 1, 0, 2, 5, 31, 136, 1040 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Let G_n be an n-vertex simple graph, with a(G_n) automorphisms. Then l(G_n) = n!/a(G_n) is the number of labeled copies of G_n. So a(n) is the number of G_n for which n divides l(G_n). REFERENCES John P. McSorley, Smallest labelled class (and largest automorphism group) of a tree T_{s,t} and good labellings of a graph, preprint, (2016). R. C. Read, R. J. Wilson, An Atlas of Graphs, Oxford Science Publications, Oxford University Press, (1998). LINKS EXAMPLE If n=3 then both G_3 = K_1 union K_2 and its complement have a(G_3)=2, so l(G_3) = 3!/2 = 3, and so 3 divides l(G_3); no other graphs G_3 satisfy this, so a(3) = 2. CROSSREFS Cf. A000088. Sequence in context: A000133 A059086 A215168 * A107389 A261750 A189559 Adjacent sequences:  A266475 A266476 A266477 * A266479 A266480 A266481 KEYWORD nonn,hard,more AUTHOR John P. McSorley, Dec 29 2015 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 8 16:23 EDT 2022. Contains 356015 sequences. (Running on oeis4.)