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%I #19 Dec 26 2017 18:39:31
%S 0,1,2,12,56,290,1752,12278,98240,884178,8841800,97259822,1167117888,
%T 15172532570,212415456008,3186231840150,50979709442432,
%U 866655060521378,15599791089384840,296396030698311998,5927920613966240000,124486332893291040042
%N Expansion of (2*x*exp(x)-3)/(1-x).
%C Number of bisymmetric and quasitrivial binary operations on {1,...,n} that have annihilator elements.
%H Robert G. Wilson v, <a href="/A296944/b296944.txt">Table of n, a(n) for n = 0..449</a>
%H J. Devillet, <a href="https://arxiv.org/abs/1712.07856">Bisymmetric and quasitrivial operations: characterizations and enumerations</a>, arXiv:1712.07856 [math.RA] (2017).
%F a(n) = A296943(n)-2, a(0) = 0, a(1) = 1.
%t Join[{0, 1}, Delete[ Range[0, 21]! CoefficientList[ Series[(2x*Exp[x] -3)/(1 -x), {x, 0, 21}], x], {{1}, {2}}]] (* _Robert G. Wilson v_, Dec 22 2017 *)
%Y Cf. A296943.
%K nonn,easy
%O 0,3
%A _J. Devillet_, Dec 22 2017
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