Expansion of E.g.f. (1 + 2*x + x^2/2) * sech(x).

Terms

a(0) =1a(1) =2a(2) =0a(3) =-6a(4) =-1a(5) =50a(6) =14a(7) =-854a(8) =-323a(9) =24930a(10) =11804a(11) =-1111462a(12) =-631621a(13) =70271890a(14) =46590634a(15) =-5980829430a(16) =-4531805575a(17) =659311412930a(18) =562021682744