OFFSET
1,2
COMMENTS
A subsequence of A095862.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
Sam Vandervelde, The Mandelbrot Competition, round 2, 2006-07, asked for the smallest composite number in this list.
EXAMPLE
1 is the only one-digit number with only one factor. Two-digit primes are the only two-digit numbers in the list since they have a one-digit factor (1) and a two-digit factor (themselves). Three-digit squares of two-digit primes are the only three-digit numbers in the list, since only numbers of the form p^2 can have three factors.
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Joshua Zucker, Dec 11 2006
STATUS
approved