Array read by ascending antidiagonals: A(n, k) = Sum_{j=0..k} tan(j*Pi/(1 + 2*k))^(2*n).

Terms

a(0) =1a(1) =0a(2) =2a(3) =0a(4) =3a(5) =3a(6) =0a(7) =9a(8) =10a(9) =4a(10) =0a(11) =27a(12) =90a(13) =21a(14) =5a(15) =0a(16) =81a(17) =850a(18) =371a(19) =36a(20) =6a(21) =0a(22) =243a(23) =8050a(24) =7077a(25) =1044a(26) =55a(27) =7a(28) =0a(29) =729