A085156 Powers of primes or powers of semiprimes.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, 25, 26, 27, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 43, 46, 47, 49, 51, 53, 55, 57, 58, 59, 61, 62, 64, 65, 67, 69, 71, 73, 74, 77, 79, 81, 82, 83, 85, 86, 87, 89, 91, 93, 94, 95, 97, 100, 101

Offset: 1

Author

Reinhard Zumkeller, Jun 21 2003

Keywords

• nonn

Comments

m is a term iff A067029(m) = A071178(m) and A001221(m) <= 2.

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Union of A000961 and A085155.

Cf. A001221, A067029, A071178.

Programs

Mathematica

q[n_] := Module[{e = FactorInteger[n][[;;, 2]]}, Length[e] == 1 || (Length[e] == 2 && Equal @@ e)]; Select[Range[100], q] (* Amiram Eldar, Apr 19 2025 *)

PARI

is(n)=my(f=factor(n)[, 2]); #f<2 || (#f==2 && f[1]==f[2]) \\ Charles R Greathouse IV, Oct 19 2015