Bisection of A008705.

Terms

a(0) =1a(1) =-1a(2) =-5a(3) =11a(4) =-125a(5) =1054a(6) =-209a(7) =-15625a(8) =14035a(9) =-130525a(10) =1899830a(11) =-134905a(12) =-25499225a(13) =-64447293a(14) =-133867445a(15) =6309965146a(16) =-11762712973a(17) =-29646853725a(18) =-160561408097