A175107 a(1)=1. For n >= 2, if A025474(n) is the exponent of the n-th prime-power (1 is considered the first prime-power here), then a(n) = the A025474(n)th integer from among those positive integers not yet in the sequence.

1, 2, 3, 5, 4, 6, 9, 8, 7, 10, 14, 11, 12, 13, 16, 18, 15, 17, 23, 19, 20, 21, 22, 25, 24, 26, 27, 33, 28, 29, 30, 31, 36, 32, 34, 35, 37, 38, 39, 40, 41, 43, 45, 42, 51, 44, 46, 47, 48, 49, 50, 52, 53, 55, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 73, 69, 78, 70

Offset

1,2

Comments

This sequence is a permutation of the positive integers.

Links

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

Example

9 is the 8th power of a prime. 9 = 3^2. So we want the 2nd integer (because 2 is the exponent) from among those positive integers not in the first 7 terms of the sequence. The first 7 terms are 1,2,3,5,4,6, 9. Those positive integers not yet appearing form the infinite sequence 7,8,10,11,12,13,14,15,16... The 2nd integer not yet occurring is 8. So a(9)=8.

Crossrefs

Cf. A025474.

Sequence in context: A374802 A316669 A185180 * A376685 A085181 A374351

Adjacent sequences: A175104 A175105 A175106 * A175108 A175109 A175110

Keyword

nonn

Author

Leroy Quet, Feb 11 2010

Extensions

Extended by Ray Chandler, Mar 10 2010

Status

approved