OFFSET
1,1
COMMENTS
This sequence is infinite, because 3^p is a term for all p >= 5.
It seems that the smallest p-rough exceptional number (i.e., the smallest exceptional number whose smallest prime factor is p) is p^k, where k is the smallest number such that prime(k) > 2^p (p = 2 gives 2^3 = 8, p = 3 gives 3^5 = 243, p = 5 gives 5^12 = 244140625, ...).
LINKS
M. E. Grost, The smallest number with a given number of divisors, Amer. Math. Monthly, 75 (1968), 725-729.
EXAMPLE
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Jan 22 2020
STATUS
approved