login
A348121
Numbers having more nonunitary than unitary prime divisors.
3
4, 8, 9, 16, 25, 27, 32, 36, 49, 64, 72, 81, 100, 108, 121, 125, 128, 144, 169, 180, 196, 200, 216, 225, 243, 252, 256, 288, 289, 300, 324, 343, 360, 361, 392, 396, 400, 432, 441, 450, 468, 484, 500, 504, 512, 529, 540, 576, 588, 600, 612, 625, 648, 675, 676, 684
OFFSET
1,1
COMMENTS
First differs from A080366 at n = 20.
The first 19 terms are also the first 19 powerful numbers (A001694) above 1. a(20) = 180 is the least nonpowerful term.
Numbers k such that A056169(k) < A056170(k).
LINKS
EXAMPLE
4 = 2^2 is a term since it has 1 nonunitary prime divisor, 2, and no unitary prime divisors.
180 = 2^2 * 3^2 * 5 is a term since it has 2 nonunitary prime divisors, 2 and 3, and one unitary prime divisor, 5.
MATHEMATICA
q[n_] := 2*Count[(e = FactorInteger[n][[;; , 2]]), 1] < Length[e]; Select[Range[700], q]
CROSSREFS
Subsequence of A013929.
A001694 is a subsequence.
Sequence in context: A158804 A341645 A339497 * A080366 A001694 A317102
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 01 2021
STATUS
approved