OFFSET
1,2
COMMENTS
Not a multiplicative semigroup. For example, although 10 and 21 are present, 210 is missing. Compare to A332820. - Antti Karttunen, Jan 17 2023
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 21 2019
STATUS
approved