OFFSET
1,2
COMMENTS
The sequence is conjectured to be a permutation of the positive integers although it may take a large number of terms for the primes to appear, e.g., 17 has not occurred after 100000 terms. In the same range the only fixed points are the first two terms; it is likely no more exist although this is unknown.
LINKS
Scott R. Shannon, Image of the first 100000 terms. The green line is y = n.
EXAMPLE
a(8) = 3 as a(7) = 12 which has six divisors, and 3 is the smallest unused number that shares a factor with both 12 and 6.
CROSSREFS
KEYWORD
nonn
AUTHOR
Scott R. Shannon, Aug 07 2022
STATUS
approved