OFFSET
1
COMMENTS
EXAMPLE
The sequence of sets of superior prime divisors of each positive integer begins: {}, {2}, {3}, {2}, {5}, {3}, {7}, {}, {3}, {5}, {11}, {}, {13}, {7}, {5}, {}, {17}, {}, {19}, {5}, ...
MATHEMATICA
Table[Length[Select[Divisors[n], PrimeQ[#]&&#>=n/#&]], {n, 100}]
CROSSREFS
Positions of ones are A063538.
Positions of zeros are A063539.
The inferior version is A063962.
The strictly inferior version is A333806.
The version for squarefree instead of prime divisors is A341592.
The version for prime power instead of prime divisors is A341593.
Dominates A341642 (the strictly superior version).
The version for odd instead of prime divisors is A341675.
The unique superior prime divisors of the positive positions are A341676.
A033677 selects the smallest superior divisor.
A038548 counts superior (or inferior) divisors.
A056924 counts strictly superior (or strictly inferior) divisors.
A161908 lists superior divisors.
A207375 list central divisors.
KEYWORD
nonn
AUTHOR
Gus Wiseman, Feb 19 2021
STATUS
approved