A055341 - OEIS

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A055341

Number of mobiles (circular rooted trees) with n nodes and 3 leaves.

1

1, 3, 8, 19, 37, 66, 110, 172, 257, 371, 518, 705, 939, 1226, 1574, 1992, 2487, 3069, 3748, 4533, 5435, 6466, 7636, 8958, 10445, 12109, 13964, 16025, 18305, 20820, 23586, 26618, 29933, 33549, 37482, 41751, 46375, 51372, 56762, 62566, 68803

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OFFSET

4,2

LINKS

Table of n, a(n) for n=4..44.

Index entries for sequences related to mobiles

Index entries for linear recurrences with constant coefficients, signature (3,-2,-1,0,1,2,-3,1).

FORMULA

G.f.: x^4(-x^4+2x^3+x^2+1)/((1-x^2)(1-x^3)(1-x)^3).

CROSSREFS

Column 3 of A055340.

Sequence in context: A209367 A086167 A083186 * A067332 A082535 A007326

Adjacent sequences: A055338 A055339 A055340 * A055342 A055343 A055344

KEYWORD

nonn

AUTHOR

Christian G. Bower, May 14 2000

STATUS

approved