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Number of labeled mobiles (circular rooted trees) with n nodes and 4 leaves.
2

%I #14 Mar 14 2022 07:26:04

%S 30,1500,47250,1234800,29635200,685843200,15717240000,362244960000,

%T 8476532064000,202580554176000,4963223577312000,124948285862400000,

%U 3236755595673600000,86346680044584960000,2372991796225290240000

%N Number of labeled mobiles (circular rooted trees) with n nodes and 4 leaves.

%H Georg Fischer, <a href="/A055351/b055351.txt">Table of n, a(n) for n = 5..250</a>

%H <a href="/index/Mo#mobiles">Index entries for sequences related to mobiles</a>

%t m = 20; L[x_] = Log[1 - x] + O[x]^m // Normal; A[_] = 0;

%t Do[A[x_] = x y - x L[A[x]] + O[x]^k // Normal // Expand, {k, m}];

%t Drop[(SeriesCoefficient[#, {y, 0, 4}] & /@ CoefficientList[A[x], x]) * Range[0, m - 1]!, 5] (* _Jean-François Alcover_, Nov 01 2019 *)

%Y Column 4 of A055349.

%K nonn

%O 5,1

%A _Christian G. Bower_, May 15 2000