OFFSET
1,1
COMMENTS
The smallest term with 3 or more prime factors is 63 = 3*3*7 (see A217264).
The smallest term with 4 or more prime factors is 21249 = 3*3*3*787 (see A217265).
The smallest term with 5 or more prime factors is 146461 = 7*7*7*7*61.
There is no term under 10^8 with 6 or more prime factors.
The smallest term with 3 or more distinct prime factors is 3311 = 7*11*43 (see A180679).
There is no term under 10^8 with 4 or more distinct prime factors.
EXAMPLE
21 is 3*7. Both 37 and 73 are prime, so 21 is in the sequence.
63 is 3*3*7. 337, 373 and 733 are all prime, so 63 is in the sequence.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Dmitri Kamenetsky, Sep 29 2012
STATUS
approved