Skip 1, take 2, skip 3, etc.

Terms

a(0) =2a(1) =3a(2) =7a(3) =8a(4) =9a(5) =10a(6) =16a(7) =17a(8) =18a(9) =19a(10) =20a(11) =21a(12) =29a(13) =30a(14) =31a(15) =32a(16) =33a(17) =34a(18) =35a(19) =36a(20) =46a(21) =47a(22) =48a(23) =49a(24) =50a(25) =51a(26) =52a(27) =53a(28) =54a(29) =55