%I #14 Jun 01 2014 10:08:42

%S 1,18,477,15726,608499,26775630,1312423155,70609087530,4123848816585,

%T 259217370402930,17415882628886925,1243604250827128350,

%U 93931364648982616875,7474399697415548199150,624407709783640239540675

%N Number of labeled servers of dimension 18.

%H Vincenzo Librandi, <a href="/A027405/b027405.txt">Table of n, a(n) for n = 0..200</a>

%H R. Donaghey, <a href="http://dx.doi.org/10.1016/0097-3165(76)90060-1">Binomial self-inverse sequences and tangent coefficients</a>, J. Combin. Theory, Series A, 21 (1976), 155-163.

%F E.g.f.: exp( sum( ((1+x)^i-1)/i, i=1..18 ) ).

%t Table[n!*SeriesCoefficient[E^(Sum[((1+x)^i - 1)/i, {i, 1, 18}]), {x, 0, n}], {n, 0, 20}] (* _Vincenzo Librandi_, Jan 01 2013 *)

%K nonn

%O 0,2

%A _Olivier Gérard_