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

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =1a(7) =5a(8) =9a(9) =17a(10) =4a(11) =65a(12) =121a(13) =277a(14) =841a(15) =2746a(16) =441a(17) =28561a(18) =93025a(19) =312001a(20) =583696a(21) =5309441a(22) =14145121a(23) =116815697a(24) =719795241a(25) =4487760170a(26) =433763929a(27) =175081030037