a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 1, 2, 1, 1.

Terms

a(0) =1a(1) =2a(2) =1a(3) =1a(4) =3a(5) =6a(6) =14a(7) =33a(8) =79a(9) =194a(10) =482a(11) =1214a(12) =3090a(13) =7936a(14) =20544a(15) =53545a(16) =140399a(17) =370098a(18) =980226a(19) =2607242a(20) =6961462a(21) =18652112a(22) =50133616a(23) =135140598a(24) =365254226a(25) =989614976a(26) =2687312752a(27) =7312725944a(28) =19938170096a(29) =54460115308