a(n) = (1/2)*s(n), where s(n) is the n-th even number in A026177.

Terms

a(0) =2a(1) =1a(2) =5a(3) =6a(4) =8a(5) =3a(6) =11a(7) =4a(8) =14a(9) =15a(10) =17a(11) =18a(12) =20a(13) =7a(14) =23a(15) =24a(16) =26a(17) =9a(18) =29a(19) =10a(20) =32a(21) =33a(22) =35a(23) =12a(24) =38a(25) =13a(26) =41a(27) =42a(28) =44a(29) =45