A138310 a(1)=1. a(n) = smallest positive integer not occurring among the first n-1 terms of the sequence that is coprime to n and is coprime to every (nonzero) exponent in the prime factorization of n.

1, 3, 2, 5, 4, 7, 6, 11, 13, 9, 8, 17, 10, 15, 14, 19, 12, 23, 16, 21, 20, 25, 18, 29, 27, 31, 22, 33, 24, 37, 26, 39, 28, 35, 32, 41, 30, 43, 34, 47, 36, 53, 38, 45, 49, 51, 40, 55, 57, 59, 44, 61, 42, 65, 46, 67, 50, 63, 48, 71, 52, 69, 73, 77, 54, 79, 56, 75, 58, 81, 60, 83

Offset

1,2

Links

Table of n, a(n) for n=1..72.

Example

12 has the prime-factorization of 2^2 * 3^1. The positive integers that don't occur among the first 11 terms of the sequence are 10,12,14,15,16,17,18,19,... Of these integers, 17 is the smallest that is coprime to the exponents in the prime factorization of 12 (i.e., coprime to 2 and 1) and is coprime to 12. So a(12) = 17.

Crossrefs

Cf. A138308, A138311.

Sequence in context: A353904 A353780 A080261 * A270197 A332769 A191709

Adjacent sequences: A138307 A138308 A138309 * A138311 A138312 A138313

Keyword

nonn

Author

Leroy Quet, Mar 13 2008

Extensions

More terms from Max Alekseyev, Apr 24 2010

Status

approved