OFFSET
1,2
COMMENTS
The sequence is finite; after 6481 terms a(6480) = 5211 and a(6481) = 44444 resulting in a product of 5211 * 44444 = 231597684. This contains all digits 1 to 9 so the next term does not exist.
The sequence contains 40 fixed points, the last being a(5477).
LINKS
Michael S. Branicky, Table of n, a(n) for n = 1..6481
Michael S. Branicky, Python program
Scott R. Shannon, Image of the 6481 terms. The green line is a(n) = n.
EXAMPLE
a(12) = 22 as a(10) * a(11) = 10 * 11 = 110, and 22 is the smallest unused number that does not contain the digits 0 or 1.
PROG
(Python) # see linked program
CROSSREFS
KEYWORD
nonn,base,fini,full
AUTHOR
Scott R. Shannon, Apr 08 2023
STATUS
approved