Tribonacci sequences A000073 and A001590 interleaved.

Terms

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