A058521 B-trees of order 5 with n labeled leaves.

1, 1, 1, 2, 3, 4, 7, 11, 20, 36, 67, 121, 215, 377, 657, 1154, 2045, 3666, 6628, 12063, 22079, 40642, 75264, 140191, 262457, 493297, 929703, 1754941, 3314509, 6258052, 11803995, 22232306, 41801393, 78453563, 146987053, 274957984

Offset: 1

Author

N. J. A. Sloane, Dec 21 2000

Keywords

• nonn

Links

• Index entries for sequences related to rooted trees

Crossrefs

Cf. A014535, A037026.

Programs

Maple

spec := [ B, {B=Union(Z, Subst(M, B)), M=Union(Prod(Z,Z),Prod(Z,Z,Z),Prod(Z$4),Prod(Z$5))} ]: [seq(combstruct[count](spec, size=n), n=1..40)];

Mathematica

nn=38;f[x_]:=Sum[a[n]x^n,{n,0,nn}];a[0]=0;sol=SolveAlways[0==Series[f[x]-x-f[x^2+x^3+x^4+x^5],{x,0,nn}],x];Table[a[n],{n,0,nn}]/.sol  (* Geoffrey Critzer, Mar 28 2013 *)

Formula

G.f. A(x) satisfies: A(x) = x + A(x^2+x^3+x^4+x^5). [Geoffrey Critzer, Mar 28 2013]