Numbers with exactly 3 1's in ternary expansion.

Terms

a(0) =13a(1) =31a(2) =37a(3) =39a(4) =41a(5) =43a(6) =49a(7) =67a(8) =85a(9) =91a(10) =93a(11) =95a(12) =97a(13) =103a(14) =109a(15) =111a(16) =113a(17) =115a(18) =117a(19) =119a(20) =123a(21) =125a(22) =127a(23) =129a(24) =131a(25) =133a(26) =139a(27) =145a(28) =147a(29) =149