a(n) = (1/3)*(s(n) + 2), where s(n) is the n-th number congruent to 1 mod 3 in A026177.

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =3a(5) =8a(6) =10a(7) =12a(8) =5a(9) =14a(10) =16a(11) =18a(12) =7a(13) =20a(14) =22a(15) =24a(16) =9a(17) =26a(18) =28a(19) =30a(20) =11a(21) =32a(22) =34a(23) =36a(24) =13a(25) =38a(26) =40a(27) =42a(28) =15a(29) =44