G.f. A(x) satisfies: A(x) = 1 - Sum_{k=1..4} (x * A(x))^k.

Terms

a(0) =1a(1) =-1a(2) =0a(3) =1a(4) =0a(5) =-1a(6) =-5a(7) =13a(8) =5a(9) =-43a(10) =4a(11) =98a(12) =122a(13) =-638a(14) =-246a(15) =2912a(16) =-537a(17) =-9419a(18) =-1648a(19) =47005a(20) =2243a(21) =-232237a(22) =87988a(23) =904267a(24) =-351692a(25) =-4123026a(26) =1726126a(27) =20257940a(28) =-14035151a(29) =-86846040