|
%I #4 Mar 30 2012 16:48:55
%S 1,1,1,2,2,4,6,9,14,21,33,54,89,142,222,350,554,883,1406,2225,3511,
%T 5539,8768,13977,22417,36143,58483,94818,153716,248699,401054,644485,
%U 1032794,1652377,2642421,4227547,6769660,10851491,17410292,27951747
%N Number of forests of B-trees of order 3 with n labeled leaves.
%p spec := [C, {B=Union(Z, Subst(M, B)), M=Union(Prod(Z,Z),Prod(Z,Z,Z)), C=PowerSet(B)} ]; [seq(combstruct[count](spec, size=n), n=0..40)];
%Y Cf. A014535.
%K nonn
%O 0,4
%A _N. J. A. Sloane_, Dec 21 2000
|
