Numbers of the form t_n or t_n + t_{n+1} where {t_n} are the tribonacci numbers A000073.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =4a(5) =6a(6) =7a(7) =11a(8) =13a(9) =20a(10) =24a(11) =37a(12) =44a(13) =68a(14) =81a(15) =125a(16) =149a(17) =230a(18) =274a(19) =423a(20) =504a(21) =778a(22) =927a(23) =1431a(24) =1705a(25) =2632a(26) =3136a(27) =4841a(28) =5768a(29) =8904