A094681 - OEIS

A094681

Smallest number <>n, not occurring earlier and having as many distinct prime factors as n has, with a(1) = 1.

1, 3, 2, 5, 4, 10, 8, 7, 11, 6, 9, 14, 16, 12, 18, 13, 19, 15, 17, 21, 20, 24, 25, 22, 23, 28, 29, 26, 27, 42, 32, 31, 34, 33, 36, 35, 41, 39, 38, 44, 37, 30, 47, 40, 46, 45, 43, 50, 53, 48, 52, 51, 49, 55, 54, 57, 56, 62, 61, 66, 59, 58, 65, 67, 63, 60, 64, 69, 68, 78, 73, 74

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OFFSET

1,2

COMMENTS

Self-inverse integer permutation: a(a(n))=n.

LINKS

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

Index entries for sequences that are permutations of the natural numbers

PROG

Contribution from Franklin T. Adams-Watters, Apr 16 2009: (Start)

(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