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

1,4

Links

Table of n, a(n) for n=1..36.

Index entries for sequences related to rooted trees

Formula

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

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 *)

Crossrefs

Cf. A014535, A037026.

Sequence in context: A339548 A256994 A107481 * A372266 A116628 A140463

Adjacent sequences: A058518 A058519 A058520 * A058522 A058523 A058524

Keyword

nonn

Author

N. J. A. Sloane, Dec 21 2000

Status

approved