A213439 - OEIS

%I N1106 #6 Jun 11 2012 22:02:33

%S 1,3,8,25,72,231,696,2268,7030,23155,73188,242957,778946,2601345,

%T 8430992,28289598,92470194,311472985,1025114180,3463982109,

%U 11465054942,38846071490,129180293184,438697998100,1464716085664,4984101484479,16698145444260,56918978668875

%N A000136(n)/2.

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

%Y Cf. A000136, A000560.

%K nonn

%O 2,2

%A _N. J. A. Sloane_, Jun 11 2012