A026491 a(n) = least k > a(n-1) such that t(k) = t(n), for n >= 1, where t = A001285 (Thue-Morse sequence).

1, 4, 5, 8, 10, 12, 13, 16, 17, 20, 21, 24, 26, 28, 29, 32, 34, 36, 37, 40, 42, 44, 45, 48, 49, 52, 53, 56, 58, 60, 61, 64, 65, 68, 69, 72, 74, 76, 77, 80, 81, 84, 85, 88, 90, 92, 93, 96, 98, 100, 101, 104, 106, 108, 109, 112, 113, 116, 117