cp's OEIS Frontend

A005501 Number of unrooted triangulations of a pentagon with n internal nodes.

%I A005501 M3488 #36 Feb 23 2021 10:06:09
%S A005501 1,4,14,69,396,2503,16905,119571,874771,6567181,50329363,392328944,
%T A005501 3102523829,24839151315,201011560316,1642124006250,13527821578754,
%U A005501 112279051170871,938188211057701,7887160187935198,66672792338916470,566452703137103796,4834838039006782636
%N A005501 Number of unrooted triangulations of a pentagon with n internal nodes.
%C A005501 These are also called [n,2]-triangulations.
%C A005501 Graphs can be enumerated and counted using the tool "plantri", in particular the command "./plantri -s -P5 -c2m2 [n]". - _Manfred Scheucher_, Mar 08 2018
%D A005501 C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979.
%D A005501 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A005501 Andrew Howroyd, <a href="/A005501/b005501.txt">Table of n, a(n) for n = 0..200</a>
%H A005501 G. Brinkmann and B. McKay, <a href="http://users.cecs.anu.edu.au/~bdm/plantri/">Plantri (program for generation of certain types of planar graph)</a>
%H A005501 C. F. Earl and L. J. March, <a href="/A005500/a005500_1.pdf">Architectural applications of graph theory</a>, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979. (Annotated scanned copy)
%H A005501 C. F. Earl & N. J. A. Sloane, <a href="/A005500/a005500.pdf">Correspondence, 1980-1981</a>
%F A005501 a(n) = (A005506(n) + A002711(n))/2. - _Max Alekseyev_, Oct 29 2012
%Y A005501 Column k=2 of the array in A169808.
%Y A005501 Cf. A002711, A005506.
%K A005501 nonn
%O A005501 0,2
%A A005501 _N. J. A. Sloane_
%E A005501 a(6)-a(11) from _Manfred Scheucher_, Mar 08 2018
%E A005501 Name clarified and terms a(12) and beyond from _Andrew Howroyd_, Feb 22 2021