

A100826


a(1) = 1; a(n+1) = gcd(n,a(n))th smallest positive integer not already in the sequence.


2



1, 2, 4, 3, 5, 10, 7, 14, 8, 6, 11, 22, 12, 9, 13, 15, 16, 17, 18, 19, 20, 21, 23, 46, 25, 50, 26, 24, 30, 27, 31, 62, 29, 28, 33, 32, 37, 74, 35, 34, 38, 36, 44, 39, 40, 47, 41, 42, 52, 43, 45, 51, 48, 49, 53, 54, 56, 55, 57, 58, 60, 59, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71
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OFFSET

1,2


COMMENTS

Probably a permutation of the positive integers.
This is a permutation iff, infinitely often, gcd(n, a(n)) = 1. Through n = 1000, gcd(n, a(n)) = 1 612 times, which is consistent with the natural conjecture that this is true with density 6/Pi^2 ~ 0.6079....  Franklin T. AdamsWatters, Nov 28 2006


LINKS

Franklin T. AdamsWatters, Table of n, a(n) for n = 1..1000


MATHEMATICA

a[1] = 1; a[n_] := a[n] = Complement[ Range[250], Table[a[i], {i, n  1}]][[GCD[n  1, a[n  1]]]]; Table[ a[n], {n, 60}] (* Robert G. Wilson v, Jan 10 2005 *)


CROSSREFS

Cf. A125628.
Sequence in context: A091449 A100834 A264996 * A232799 A276472 A245702
Adjacent sequences: A100823 A100824 A100825 * A100827 A100828 A100829


KEYWORD

nonn


AUTHOR

Leroy Quet, Jan 06 2005


EXTENSIONS

More terms from Robert G. Wilson v, Jan 10 2005


STATUS

approved



