A121274 a(n) = n-th integer from among those positive integers which are coprime to (n-th integer from among those positive integers which are coprime to n).
1, 2, 5, 4, 13, 6, 13, 14, 9, 10, 31, 17, 29, 14, 33, 16, 49, 18, 47, 23, 21, 22, 67, 24, 25, 36, 67, 37, 107, 30, 61, 55, 33, 34, 55, 36, 77, 38, 79, 65, 143, 53, 93, 58, 45, 61, 139, 57, 77, 76, 127, 80, 157, 65, 113, 85, 57, 72, 221, 60, 125, 62, 63, 64, 100, 79, 141, 81
Offset: 1
Keywords
Examples
6 is the 5th positive integer which is coprime to 5. (1,2,3,4,6,7,8.... is the sequence of positive integers which are coprime to 5 and 6 is the 5th such integer.) 1,5,7,11,13,17,19,... are the positive integers which are coprime to 6. 13 is the 5th of these integers, so a(5) = 13.
Crossrefs
Cf. A069213.
Extensions
Extended by Ray Chandler, Aug 29 2006