The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A184973 Number of connected 7-regular simple graphs on 2n vertices with girth exactly 3. 8
 0, 0, 0, 0, 1, 5, 1547, 21609300, 733351105933 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,6 LINKS FORMULA a(n) = A014377(n) - A181153(n). EXAMPLE a(0)=0 because even though the null graph (on zero vertices) is vacuously 7-regular and connected, since it is acyclic, it has infinite girth. The a(4)=1 complete graph on 8 vertices is 7-regular; it has 28 edges and 56 triangles. MATHEMATICA A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {_, _}][[All, 2]]]; A014377 = A@014377; A181153 = A@181153; a[n_] := A014377[[n + 1]] - A181153[[n + 1]]; a /@ Range[0, 8] (* Jean-François Alcover, Jan 27 2020 *) CROSSREFS Connected 7-regular simple graphs with girth at least g: A014377 (g=3), A181153 (g=4). Connected 7-regular simple graphs with girth exactly g: this sequence (g=3), A184974 (g=4). Sequence in context: A181992 A145694 A184970 * A184971 A014377 A165628 Adjacent sequences:  A184970 A184971 A184972 * A184974 A184975 A184976 KEYWORD nonn,more,hard AUTHOR Jason Kimberley, Feb 28 2011 STATUS approved

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

Last modified January 22 02:46 EST 2022. Contains 350481 sequences. (Running on oeis4.)