Zeroless analog of tribonacci numbers.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =5a(5) =9a(6) =17a(7) =31a(8) =57a(9) =15a(10) =13a(11) =85a(12) =113a(13) =211a(14) =49a(15) =373a(16) =633a(17) =155a(18) =1161a(19) =1949a(20) =3265a(21) =6375a(22) =11589a(23) =21229a(24) =39193a(25) =7211a(26) =67633a(27) =11437a(28) =86281a(29) =165351