0,3

Also number of 2-connected outerplanar graphs on n unlabeled nodes. - S. R. Finch (Steven.Finch(AT)inria.fr), Dec 09 2004

Guanzhang Hu, Group theory method for enumeration of outerplanar graphs, Acta Math. Appl. Sinica 14 (1998) 381-387.

P. Lisonek, Closed forms for the number of polygon dissections. Journal of Symbolic Computation 20 (1995), 595-601.

T. S. Motzkin, Relations between hypersurface cross ratios and a combinatorial formula for partitions of a polygon, for permanent preponderance and for non-associative products, Bull. Amer. Math. Soc., 54 (1948), 352-360.

R. C. Read, On general dissections of a polygon, Aequat. Math. 18 (1978), 370-388.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

S. R. Finch, Planar graph growth constants.

f[x_, n_]:=x+Sum[(1/r)*Binomial[s-2, r-1]*Binomial[r+s-1, s]*x^s, {r, 1, n}, {s, 2, n}]; F[x_, n_]:=Series[((3x^2-2*x*f[x, n]+f[x, n]^2)- (2+2*x+7*x^2-4*x*f[x, n]+2*f[x, n]^2)*f[x^2, n]+ 2*f[x^2, n]^2)/(4*(2*f[x^2, n]-1))+Sum[If[Mod[k, d]==0, EulerPhi[d]*f[x^d, n]^(k/d)/k, 0], {k, 3, n}, {d, 1, k}]/2, {x, 0, n}]; F[x, 22] (Finch)

Sequence in context: A097075 A036673 A111189 this_sequence A015951 A101531 A099607

Adjacent sequences: A001001 A001002 A001003 this_sequence A001005 A001006 A001007

nonn,nice,easy

N. J. A. Sloane (njas(AT)research.att.com).

More terms from Esa Peuha (esa.peuha(AT)helsinki.fi), Oct 21 2005