OFFSET
1,2
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..1000
Eric Weisstein's World of Mathematics, Divisor
FORMULA
A033273(a(n)) = n.
EXAMPLE
a(5) = 105 because 105 has 8 divisors {1, 3, 5, 7, 15, 21, 35, 105} among which 5 are nonprime {1, 15, 21, 35, 105} and 105 is the smallest odd with exactly 5 nonprime divisors.
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, May 29 2017
EXTENSIONS
a(35)-a(39) from Giovanni Resta, May 31 2017
STATUS
approved