A120497 Positive integers whose number of divisors is a perfect power.

1, 6, 8, 10, 14, 15, 21, 22, 24, 26, 27, 30, 33, 34, 35, 36, 38, 39, 40, 42, 46, 51, 54, 55, 56, 57, 58, 62, 65, 66, 69, 70, 74, 77, 78, 82, 85, 86, 87, 88, 91, 93, 94, 95, 100, 102, 104, 105, 106, 110, 111, 114, 115, 118, 119, 120, 122, 123, 125, 128, 129, 130, 133, 134

Offset

1,2

Links

Table of n, a(n) for n=1..64.

Mathematica

Join[{1}, Select[Range[150], GCD@@FactorInteger[DivisorSigma[0, #]][[All, 2]]>1&]] (* Harvey P. Dale, Oct 19 2022 *)

Prog

(PARI) v=[1]; for(n=2, 134, if(ispower(numdiv(n)), v=concat(v, n))); v \\ Nick Hobson, Nov 29 2006

Crossrefs

Sequence in context: A332269 A328338 A365535 * A036436 A036455 A291127

Adjacent sequences: A120494 A120495 A120496 * A120498 A120499 A120500

Keyword

easy,nonn

Author

Giovanni Teofilatto, Aug 06 2006

Extensions

More terms from Nick Hobson, Nov 29 2006

Incorrect comment removed by Charles R Greathouse IV, Mar 25 2010

Status

approved