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A120837 a(n) = the smallest positive integer which does not occur earlier in the sequence and which is coprime to the number of positive divisors of n. 0
1, 3, 5, 2, 7, 9, 11, 13, 4, 15, 17, 19, 21, 23, 25, 6, 27, 29, 31, 35, 33, 37, 39, 41, 8, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 10, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 87, 14, 85, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 12, 115, 117, 119, 121 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Sequence is a permutation of the positive integers.

LINKS

Table of n, a(n) for n=1..68.

EXAMPLE

6 has 4 positive divisors. Among those positive integers not occurring among the first 5 terms of the sequence, 9 is the smallest which is coprime to 4. So a(6) = 9. 4, 6 and 8 also do not occur among the first 5 terms of the sequence, but they are not coprime to 4.

CROSSREFS

Cf. A000005.

Sequence in context: A243352 A026184 A026208 * A208754 A180077 A095749

Adjacent sequences:  A120834 A120835 A120836 * A120838 A120839 A120840

KEYWORD

nonn

AUTHOR

Leroy Quet, Aug 18 2006

EXTENSIONS

Extended by Ray Chandler, Aug 22 2006

STATUS

approved

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Last modified November 12 04:21 EST 2019. Contains 329051 sequences. (Running on oeis4.)