A130092 Numbers with at least two factors having in their canonical prime factorization equal exponents.

6, 10, 14, 15, 21, 22, 26, 30, 33, 34, 35, 36, 38, 39, 42, 46, 51, 55, 57, 58, 60, 62, 65, 66, 69, 70, 74, 77, 78, 82, 84, 85, 86, 87, 90, 91, 93, 94, 95, 100, 102, 105, 106, 110, 111, 114, 115, 118, 119, 120, 122, 123, 126, 129, 130, 132, 133, 134, 138, 140, 141, 142

Offset: 1

Author

Reinhard Zumkeller, May 06 2007

Keywords

• nonn

Comments

Complement of A130091; A120944 and A085986 are subsequences;

a(n)>A130091(n) for n<=150, a(n) < A130091(n) for n>150.

Links

• R. Zumkeller, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Prime Factorization

Programs

Mathematica

t[n_] := FactorInteger[n][[All, 2]];s = Select[Range[400], Union[t[#]] == Sort[t[#]] &] (* A130091 *)
Complement[Range[Max[s]], s]  (* A130092 *)
(* Clark Kimberling, Mar 12 2015 *)