A100527 a(1) = 1, n>1: a(n) = smallest m<>n and not occurring earlier such that m has as many prime-factors as n has (with repetition).

1, 3, 2, 6, 7, 4, 5, 12, 10, 9, 13, 8, 11, 15, 14, 24, 19, 20, 17, 18, 22, 21, 29, 16, 26, 25, 28, 27, 23, 42, 37, 48, 34, 33, 38, 40, 31, 35, 46, 36, 43, 30, 41, 45, 44, 39, 53, 32, 51, 52, 49, 50, 47, 56, 57, 54, 55, 62, 61, 81, 59, 58, 66, 96, 69, 63, 71, 70, 65, 68, 67, 80

Offset

1,2

Comments

a(a(n))=n: a self-inverse permutation with A001222(a(n))=A001222(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
newvect(n)=local(v); v=vector(n); for(k=1, n, v[k]=nextnew(v, k)); v
R(n, m)=bigomega(n)==bigomega(m)&&n!=m||n==1&&m==1
newvect(80) (End)

Crossrefs

Cf. A094681, A159588. [From Franklin T. Adams-Watters, Apr 16 2009]

Sequence in context: A267100 A178754 A276446 * A276445 A063946 A154441

Adjacent sequences: A100524 A100525 A100526 * A100528 A100529 A100530

Keyword

nonn

Author

Reinhard Zumkeller, Nov 25 2004

Extensions

Values through a(72) verified by [From Franklin T. Adams-Watters, Apr 16 2009]

Status

approved