0,4

Inverse Euler transform of A005470. - Christian G. Bower, May 16 2003

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

R. J. Wilson, Introduction to Graph Theory, Academic Press, NY, 1972, p. 162.

David Wasserman, Brendan McKay and Georg Grasegger, Table of n, a(n) for n = 0..13

Steven R. Finch, Mathematical Constants II, Encyclopedia of Mathematics and Its Applications, Cambridge University Press, Cambridge, 2018.

E. Friedman, Illustration of small graphs

Brendan McKay, Planar graphs

N. J. A. Sloane, Transforms

Peter Steinbach, Field Guide to Simple Graphs, Volume 1, Part 17 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)

Eric Weisstein's World of Mathematics, Planar Connected Graph

a(3) = 2 since the path o-o-o and the triangle are the two connected planar simple graphs on three nodes.

a[n_Integer?NonNegative] := a[n] = Module[{m, s, g}, s = Subsets[Range[n], {2}]; m = Length[s]; g = Graph[Range[n], UndirectedEdge @@@ #] & /@ (Pick[s, #, 1] & /@ (IntegerDigits[#, 2, m] & /@ Range[0, 2^m - 1])); Length[DeleteDuplicates[Select[Select[g, ConnectedGraphQ], PlanarGraphQ], IsomorphicGraphQ]]]; Table[a[n], {n, 0, 6}] (* Robert P. P. McKone, Oct 14 2023 *)

(nauty) geng -c $n | planarg -q | countg -q # Georg Grasegger, Jul 06 2023

Row sums of A049334.

The labeled version is A096332.

Cf. A005470, A126201.

Sequence in context: A020095 A026991 A049379 * A073964 A079457 A321911

Adjacent sequences: A003091 A003092 A003093 * A003095 A003096 A003097

nonn,nice,hard,more,core

More terms from Brendan McKay

a(12) added by Brendan McKay, Dec 06 2014

a(13) added by Georg Grasegger, Jul 06 2023

approved