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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A007100 Number of labeled trivalent (or cubic) 3-connected graphs with 2n nodes. (Formerly M5343) 2
 1, 70, 16800, 9238320, 9520156800, 16305064776000, 42856575521760000, 163329351308323200000, 864876880105205071104000, 6155146233167046820024320000, 57316399761348433188962519040000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 REFERENCES R. W. Robinson, personal communication. R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS R. W. Robinson, Table of n, a(n) for n = 2..28 R. W. Robinson, Cubic labeled graphs, computer print-out, n.d. (see last page) FORMULA a(n) = (2*n)!*r(n)/(3*n*2^n) where r(2) = 1 and r(n) = (3*n-2) * (r(n-1) + Sum_{i=2..n-2} r(i) * r(n-i)). - Sean A. Irvine, Oct 11 2017 CROSSREFS Sequence in context: A229776 A362169 A231054 * A103157 A007099 A004109 Adjacent sequences: A007097 A007098 A007099 * A007101 A007102 A007103 KEYWORD nonn AUTHOR N. J. A. Sloane. 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 June 3 18:44 EDT 2023. Contains 363116 sequences. (Running on oeis4.)