Array read by ascending antidiagonals: A(n,k)=4^k*Sum_{j=1..n} sin(2*j*Pi/(2*n+1))^(2*k).

Terms

a(0) =0a(1) =1a(2) =0a(3) =2a(4) =3a(5) =0a(6) =3a(7) =5a(8) =9a(9) =0a(10) =4a(11) =7a(12) =15a(13) =27a(14) =0a(15) =5a(16) =9a(17) =21a(18) =50a(19) =81a(20) =0a(21) =6a(22) =11a(23) =27a(24) =70a(25) =175a(26) =243a(27) =0a(28) =7a(29) =13