Position of the first n in A026400.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =7a(5) =8a(6) =11a(7) =15a(8) =16a(9) =21a(10) =24a(11) =29a(12) =30a(13) =37a(14) =45a(15) =49a(16) =50a(17) =59a(18) =64a(19) =74a(20) =76a(21) =87a(22) =99a(23) =100a(24) =110a(25) =117a(26) =128a(27) =130a(28) =133a(29) =157