OFFSET
0,6
COMMENTS
Because the triangle A051031 is symmetric, a(n) is also the number of (2n-8)-regular graphs on 2n vertices.
LINKS
Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth at least g
M. Meringer, Tables of Regular Graphs
M. Meringer, Fast generation of regular graphs and construction of cages, J. Graph Theory 30 (2) (1999) 137-146.
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Septic Graph
FORMULA
Euler transformation of A014377.
MATHEMATICA
(* EulerTransform is defined in A005195 *)
EulerTransform[Rest @ A014377] (* Jean-François Alcover, Dec 04 2019, updated Mar 18 2020 *)
CROSSREFS
7-regular simple graphs: A014377 (connected), A165877 (disconnected), this sequence (not necessarily connected).
KEYWORD
nonn,hard,more
AUTHOR
Jason Kimberley, Sep 22 2009
EXTENSIONS
Cross-references edited by Jason Kimberley, Nov 07 2009 and Oct 17 2011
a(9)-a(11) from Andrew Howroyd, Mar 09 2020
a(12) from Andrew Howroyd, May 19 2020
STATUS
approved