a(n)=det(M_n) where M_n is the n X n matrix m(i,j)=1 if sigma(i+j) is even, 0 otherwise.

Terms

a(0) =0a(1) =-1a(2) =-1a(3) =2a(4) =0a(5) =-2a(6) =-9a(7) =9a(8) =-13a(9) =-40a(10) =52a(11) =16a(12) =3a(13) =3a(14) =-25a(15) =150a(16) =73a(17) =-119a(18) =435a(19) =-409a(20) =-1479a(21) =-1526a(22) =2783a(23) =-1065a(24) =-7623a(25) =-6534a(26) =-2961a(27) =10905a(28) =-7625a(29) =-49205