Positions of even numbers in A003072.

Terms

a(0) =2a(1) =4a(2) =6a(3) =9a(4) =10a(5) =12a(6) =14a(7) =16a(8) =19a(9) =20a(10) =24a(11) =26a(12) =27a(13) =29a(14) =30a(15) =32a(16) =33a(17) =36a(18) =37a(19) =40a(20) =42a(21) =43a(22) =44a(23) =47a(24) =49a(25) =52a(26) =55a(27) =58a(28) =59a(29) =61