a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-1)*a(1) for n >= 4.

Terms

a(0) =1a(1) =0a(2) =1a(3) =2a(4) =4a(5) =9a(6) =22a(7) =56a(8) =146a(9) =388a(10) =1048a(11) =2869a(12) =7942a(13) =22192a(14) =62510a(15) =177308a(16) =506008a(17) =1451866a(18) =4185788a(19) =12119696a(20) =35227748a(21) =102753800a(22) =300672368a(23) =882373261a(24) =2596389190a(25) =7658677856a(26) =22642421206a(27) =67081765932a(28) =199128719896a(29) =592179010350