A006401 - OEIS

%I M1384 #15 Mar 31 2017 03:50:15

%S 1,1,2,5,10,28,86,285,1055,4211

%N Number of connected planar maps without vertices of degree 1.

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

%H Timothy R. Walsh, <a href="http://dx.doi.org/10.1137/0604018">Generating nonisomorphic maps without storing them</a>, SIAM J. Algebraic Discrete Methods 4 (1983), no. 2, 161-178.

%K nonn,more

%O 3,3

%A _N. J. A. Sloane_.

%E a(11)-a(12) from _Sean A. Irvine_, Mar 31 2017