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A055350 Number of labeled mobiles (circular rooted trees) with n nodes and 3 leaves. 2
8, 220, 4200, 71400, 1176000, 19474560, 330220800, 5787936000, 105380352000, 1997835840000, 39477236198400, 813155511168000, 17453093898240000, 390070546145280000, 9070029416448000000, 219204470936715264000 (list; graph; refs; listen; history; text; internal format)
OFFSET
4,1
LINKS
MATHEMATICA
m = 20;
L[x_] = Log[1-x] + O[x]^m // Normal;
A[_] = 0;
Do[A[x_] = x y - x L[A[x]] + O[x]^k // Normal // Expand, {k, m}];
Drop[(SeriesCoefficient[#, {y, 0, 3}]& /@ CoefficientList[A[x], x]) * Range[0, m-1]!, 4] (* Jean-François Alcover, Nov 01 2019 *)
CROSSREFS
Column 3 of A055349.
Sequence in context: A305517 A298964 A298455 * A183261 A316954 A299734
KEYWORD
nonn
AUTHOR
Christian G. Bower, May 15 2000
STATUS
approved

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Last modified July 14 12:35 EDT 2024. Contains 374318 sequences. (Running on oeis4.)