OFFSET
1,2
COMMENTS
Strongly refactorable numbers correspond to A141586.
Is a(n) > 0 for any n > 0 ?
LINKS
Rémy Sigrist, Table of n, a(n) for n = 1..10000
Rémy Sigrist, Colored logarithmic scatterplot of the first 100000 terms (where the color is function of A000005(n))
EXAMPLE
For n = 3:
- the divisors of 3 are: 1, 3,
- the corresponding numbers of divisors are: 1, 2,
- 2 does not divide 3,
- the divisors of 2*3 are: 1, 2, 3, 6,
- the corresponding numbers of divisors are: 1, 2, 2, 4,
- 4 does not divide 2*3,
- the divisors of 2*2*3 are: 1, 2, 3, 4, 6, 12,
- the corresponding numbers of divisors are: 1, 2, 2, 3, 4, 6,
- they all divide 2*2*3,
- hence a(3) = 2*2*3 = 12.
PROG
(PARI) a(n) = while (1, my (m=n); fordiv (m, d, m=lcm(m, numdiv(d))); if (n==m, return (n), n=m))
CROSSREFS
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Mar 05 2019
STATUS
approved