a(n+1) = Sum_{k=0..floor(n/4)} a(k) * a(n-k).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =3a(7) =5a(8) =8a(9) =16a(10) =29a(11) =53a(12) =98a(13) =196a(14) =376a(15) =723a(16) =1393a(17) =2786a(18) =5474a(19) =10752a(20) =21128a(21) =42979a(22) =85905a(23) =171810a(24) =343522a(25) =703270a(26) =1421998a(27) =2875847a(28) =5817194a(29) =11978061