A058518 - OEIS

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A058518

Number of forests of B-trees of order 3 with n labeled leaves.

1, 1, 1, 2, 2, 4, 6, 9, 14, 21, 33, 54, 89, 142, 222, 350, 554, 883, 1406, 2225, 3511, 5539, 8768, 13977, 22417, 36143, 58483, 94818, 153716, 248699, 401054, 644485, 1032794, 1652377, 2642421, 4227547, 6769660, 10851491, 17410292, 27951747

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..39.

MAPLE

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)];

CROSSREFS

Cf. A014535.

Sequence in context: A274147 A226496 A047084 * A018139 A293640 A025049

Adjacent sequences: A058515 A058516 A058517 * A058519 A058520 A058521

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Dec 21 2000

STATUS

approved