A022562 Number of connected claw-free unlabeled graphs on n nodes.
1, 1, 2, 5, 14, 50, 191, 881, 4494, 26389, 184749, 1728404, 23805256, 491544474, 14491876320
Offset: 1
Links
- R. Faudree, E. Flandrin and Z. Ryjacek, Claw-free graphs - a survey, Discr. Math., 164 (1997), 87-147.
- F. Hüffner, tinygraph, software for generating integer sequences based on graph properties, version 8489dde.
- Gordon Royle, 1728404 distinct 12-vertex connected clawfree graphs
- Gordon Royle, g6 format
- Eric Weisstein's World of Mathematics, Claw-Free Graph
- Wikipedia, Claw-free Graph
Programs
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Mathematica
EulerInvTransform[seq_] := Module[{final = {}}, For[i = 1, i <= Length[seq], i++, AppendTo[final, i*seq[[i]] - Sum[final[[d]]*seq[[i - d]], {d, i - 1}]]]; Table[Sum[MoebiusMu[i/d]*final[[d]], {d, Divisors[i]}]/i, {i, Length[seq]}]]; A086991 = Cases[Import["https://oeis.org/A086991/b086991.txt", "Table"], {, }][[All, 2]]; EulerInvTransform[A086991] (* Jean-François Alcover, Aug 20 2019, code due to Gus Wiseman *)
Formula
Inverse Euler transform of A086991. - Andrew Howroyd, Nov 03 2017
Extensions
Corrected and extended by Gordon F. Royle, May 16 2003
Term a(14) added by Gordon F. Royle, Aug 06 2008
Term a(15) added using tinygraph by Falk Hüffner, Jan 12 2016