Finch (2001, 2003) defines a -rough (or -jagged) number to be positive integer all of whose prime
factors are greater than or equal to .
Greene and Knuth define "unusual numbers" as numbers whose greatest prime factor
is greater than or equal to , and these number are dubbed "-rough" or "-jagged" by Finch (2001, 2003). The first few unusual
numbers are 2, 3, 4, 5, 6, 7, 9, 10, 11, 13, ... (OEIS A063538),
which turn out to not be so unusual after all (Greene and Knuth 1990, Finch 2001).
The first few "usual" numbers are then 8, 12, 16, 18, 24, 27, 30, ... (OEIS
A063539).
-rough (or 
-jagged) number to be positive integer all of whose prime
factors are greater than or equal to 
.
whose greatest prime factor
is greater than or equal to 
, and these number are dubbed "
-rough" or "
-jagged" by Finch (2001, 2003). The first few unusual
numbers are 2, 3, 4, 5, 6, 7, 9, 10, 11, 13, ... (OEIS A063538),
which turn out to not be so unusual after all (Greene and Knuth 1990, Finch 2001).
The first few "usual" numbers are then 8, 12, 16, 18, 24, 27, 30, ... (OEIS
A063539).
is greater than 
is 
(Schroeppel 1972).
