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A159588 a(n) is the smallest number not yet in the sequence with the same number of prime factors as n (with repetition), but relatively prime to n. 2
1, 3, 2, 9, 7, 25, 5, 27, 4, 21, 13, 125, 11, 15, 14, 81, 19, 175, 17, 63, 10, 35, 29, 625, 6, 33, 8, 45, 23, 343, 37, 243, 26, 39, 22, 875, 31, 49, 34, 189, 43, 275, 41, 75, 28, 51, 53, 3125, 38, 99, 46, 105, 47, 1225, 57, 135, 55, 65, 61, 2401, 59, 69, 20, 729, 58, 245, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is a self-inverse permutation of the positive integers.

LINKS

Table of n, a(n) for n=1..67.

PROG

(PARI) invect(v, n, x)=for(i=1, n, if(v[i]==x, return(1))); 0

nextnew(v, n)=local(k); k=1; while(!R(n, k)||invect(v, n-1, k), k++); k

newvect(n)=local(v); v=vector(n); for(k=1, n, v[k]=nextnew(v, k)); v

R(n, m)=bigomega(n)==bigomega(m)&&gcd(n, m)==1

newvect(80)

CROSSREFS

Cf. A001222, A100527, A159587.

Sequence in context: A118306 A237651 A124003 * A321572 A118045 A276023

Adjacent sequences:  A159585 A159586 A159587 * A159589 A159590 A159591

KEYWORD

nonn

AUTHOR

Franklin T. Adams-Watters, Apr 16 2009

STATUS

approved

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Last modified October 17 01:03 EDT 2019. Contains 328103 sequences. (Running on oeis4.)