a(n) = (a(n-1)*a(n-3) - a(n-2)^2) / a(n-4), with a(0) = 0, a(1) = a(2) = a(3) = 1, a(4) = -1.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =-1a(5) =-2a(6) =-3a(7) =-1a(8) =7a(9) =11a(10) =20a(11) =-19a(12) =-87a(13) =-191a(14) =-197a(15) =1018a(16) =2681a(17) =8191a(18) =-5841a(19) =-81289a(20) =-261080a(21) =-620551a(22) =3033521a(23) =14480129a(24) =69664119a(25) =-2664458a(26) =-1612539083a(27) =-7758440129a(28) =-37029252553a(29) =181003520899