Triangle of coefficients of (1/sec^2(x))*D^n(sec^2(x)) in powers of t = tan(x), where D = d/dx.

Terms

a(0) =1a(1) =0a(2) =2a(3) =2a(4) =0a(5) =6a(6) =0a(7) =16a(8) =0a(9) =24a(10) =16a(11) =0a(12) =120a(13) =0a(14) =120a(15) =0a(16) =272a(17) =0a(18) =960a(19) =0a(20) =720a(21) =272a(22) =0a(23) =3696a(24) =0a(25) =8400a(26) =0a(27) =5040a(28) =0a(29) =7936