a(n) = n! * [x^n] (tanh(x) + x*(2*x*tanh(x) - 1)*sech(x)^2)/8.

Terms

a(0) =0a(1) =0a(2) =0a(3) =2a(4) =0a(5) =-48a(6) =0a(7) =1632a(8) =0a(9) =-79360a(10) =0a(11) =5306880a(12) =0a(13) =-469733376a(14) =0a(15) =53305204736a(16) =0a(18) =0a(20) =0a(22) =0a(24) =0a(26) =0a(28) =0