%I #13 Jun 01 2014 02:14:06
%S 1,4,22,144,1074,8904,80676,789408,8267436,92024496,1082549736,
%T 13396319424,173709100152,2352429994464,33175988457264,
%U 486025859896704,7380209439505296,115932434008477248
%N Number of labeled servers of dimension 4.
%H Vincenzo Librandi, <a href="/A027391/b027391.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( (x*(48 + 36*x + 16*x^2 + 3*x^3))/12 ).
%t Table[n! * SeriesCoefficient[E^((x * (48 + 36 * x + 16 * x^2 + 3 * x^3))/12), {x, 0, n}], {n, 0, 20}] (* _Vincenzo Librandi_, Dec 31 2012 *)
%K nonn
%O 0,2
%A _Olivier GĂ©rard_