cp's OEIS Frontend

A281586 E.g.f.: z*(((exp(z)+1)/((exp(z)+2*exp(-z/2)*cos(z*sqrt(3)/2))/3))-1).

%I A281586 #12 Mar 15 2020 04:04:01
%S A281586 0,1,2,3,-4,-15,-54,133,792,4293,-15130,-123849,-895212,4101799,
%T A281586 42732522,386103915,-2177360656,-27544520691,-298649804706,
%U A281586 1999963458217,29765143177020,376514568163377,-2919514870785766,-49968285360277437,-722370834074695896,6365117686550339275
%N A281586 E.g.f.: z*(((exp(z)+1)/((exp(z)+2*exp(-z/2)*cos(z*sqrt(3)/2))/3))-1).
%p A281586 A281586_list := proc(len) z*(((exp(z)+1)/((exp(z)+2*exp(-z/2)* cos(z*sqrt(3)/2))/3))-1); series(%,z,len+1); seq(k!*coeff(%,z,k),k=0..len) end: A281586_list(20);
%o A281586 (Sage) # uses[SIB from A281588]
%o A281586 A281586_list = lambda len: SIB(len, 3)
%o A281586 print(A281586_list(26))
%Y A281586 a(n) = A215064(n,1).
%K A281586 sign
%O A281586 0,3
%A A281586 _Peter Luschny_, Jan 25 2017