Skew triangle associated to the Euler numbers.

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =-4a(5) =1a(6) =0a(7) =0a(8) =-12a(9) =1a(10) =0a(11) =0a(12) =16a(13) =-24a(14) =1a(15) =0a(16) =0a(17) =0a(18) =80a(19) =-40a(20) =1a(21) =0a(22) =0a(23) =0a(24) =-64a(25) =240a(26) =-60a(27) =1a(28) =0a(29) =0