%I #11 Nov 02 2015 11:00:42

%S 1,25,1317,96012,8976600,1027205280,139315157730,21864486188160,

%T 3898841480307900,778680435365714700,172192746831203449890,

%U 41765231538761743574100,11024455369912310561835600

%N Number of labeled planar 2-connected graphs with no vertex of degree 2 and with n vertices.

%C By empirical evidence, the terms possess a curious prime factor behavior. E.g. 2^4*3^4*5^2*7*11*13^2 divides a(16)=11024455369912310561835600.

%H A. Gagarin et al., <a href="/A104593/b104593.txt">Table of n, a(n) for n = 4..20</a>

%H A. Gagarin, G. Labelle and P. Leroux, <a href="http://arxiv.org/abs/math/0406140">Counting labeled projective-planar graphs without a K_{3,3}-subdivision</a>, arXiv:math/0406140 [math.CO], 2004-2006.

%Y Cf. A104592.

%K nonn

%O 4,2

%A _Valery A. Liskovets_, Mar 22 2005