Main diagonal of triangle A098495.

Terms

a(0) =1a(1) =-1a(2) =1a(3) =-7a(4) =76a(5) =-989a(6) =15289a(7) =-275807a(8) =5702887a(9) =-133121449a(10) =3464398070a(11) =-99482086439