A138309 a(1)=1. a(n) = smallest integer > a(n-1) that is coprime to every (nonzero) exponent in the prime factorization of n.

1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 46, 47, 48, 49, 51, 53, 54, 55, 57, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 77, 78, 79, 80, 81, 82, 83, 84, 85

Offset

1,2

Links

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

Example

24 has the prime-factorization of 2^3 * 3^1. The smallest integer > a(23)=26 that is coprime to 3 and 1 is 28. (27 is not coprime to 3.) So a(24)=28.

Crossrefs

Cf. A138308, A138311.

Sequence in context: A183292 A039193 A028798 * A184514 A001068 A039145

Adjacent sequences: A138306 A138307 A138308 * A138310 A138311 A138312

Keyword

nonn

Author

Leroy Quet, Mar 13 2008

Extensions

More terms from Sean A. Irvine, Mar 07 2010

Status

approved