OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Fixed Point
Eric Weisstein's World of Mathematics, Map
EXAMPLE
The prime signature of 12 (2^2*3^1) is (2,1). Since (2,1) contains at least two distinct numbers, and since each number that appears in (2,1) appears exactly as often as any other number that appears, 12 belongs to this sequence.
MATHEMATICA
aQ[n_] := Length[v = Values @ Counts @ FactorInteger[n][[;; , 2]]] > 1 && Length @ Union @ v == 1; Select[Range[250], aQ] (* Amiram Eldar, Aug 08 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Matthew Vandermast, Jan 04 2011
STATUS
approved