a(n) = -c(n-1) * c(n-2) * c(n+3) where c(n) = A006769(n).

Terms

a(0) =0a(1) =0a(2) =1a(3) =-3a(4) =-5a(5) =-14a(6) =-8a(7) =69a(8) =-435a(9) =2065a(10) =3612a(11) =28888a(12) =-43355a(13) =-2616119a(14) =28076979a(15) =-332513754a(16) =331948240a(17) =8280062505a(18) =641260644409