Triangle of tangent numbers.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =8a(5) =1a(6) =16a(7) =20a(8) =1a(9) =136a(10) =40a(11) =1a(12) =272a(13) =616a(14) =70a(15) =1a(16) =3968a(17) =2016a(18) =112a(19) =1a(20) =7936a(21) =28160a(22) =5376a(23) =168a(24) =1a(25) =176896a(26) =135680a(27) =12432a(28) =240a(29) =1