Table with g.f. [1-x*n-sqrt(x^2*n^2-2*n*x+1+4*x^2-4*x)]/(2*x).

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =0a(6) =1a(7) =2a(8) =3a(9) =0a(10) =1a(11) =3a(12) =8a(13) =10a(14) =0a(15) =1a(16) =4a(17) =15a(18) =36a(19) =36a(20) =0a(21) =1a(22) =5a(23) =24a(24) =84a(25) =176a(26) =137a(27) =0a(28) =1a(29) =6