Triangle of coefficients in expansion of D^n (tan x) in powers of tan x.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =2a(5) =2a(6) =8a(7) =6a(8) =16a(9) =40a(10) =24a(11) =16a(12) =136a(13) =240a(14) =120a(15) =272a(16) =1232a(17) =1680a(18) =720a(19) =272a(20) =3968a(21) =12096a(22) =13440a(23) =5040a(24) =7936a(25) =56320a(26) =129024a(27) =120960a(28) =40320a(29) =7936