Exponential Riordan array (sech(x),x).

Terms

a(0) =1a(1) =0a(2) =1a(3) =-1a(4) =0a(5) =1a(6) =0a(7) =-3a(8) =0a(9) =1a(10) =5a(11) =0a(12) =-6a(13) =0a(14) =1a(15) =0a(16) =25a(17) =0a(18) =-10a(19) =0a(20) =1a(21) =-61a(22) =0a(23) =75a(24) =0a(25) =-15a(26) =0a(27) =1a(28) =0a(29) =-427