The On-Line Encyclopedia of Integer Sequences (OEIS)

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A120497

Positive integers whose number of divisors is a perfect power.
(history; published version)

#10 by Harvey P. Dale at Wed Oct 19 10:04:56 EDT 2022

STATUS

editing

approved

#9 by Harvey P. Dale at Wed Oct 19 10:04:54 EDT 2022

MATHEMATICA

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

STATUS

approved

editing

#8 by Alois P. Heinz at Sat Feb 22 15:33:45 EST 2020

STATUS

proposed

approved

#7 by Jon E. Schoenfield at Sat Feb 22 14:44:47 EST 2020

STATUS

editing

proposed

#6 by Jon E. Schoenfield at Sat Feb 22 14:44:29 EST 2020

NAME

Natural numbers n with Positive integers whose number of divisors equal to is a perfect power.

PROG

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

EXTENSIONS

More terms from Nick Hobson , Nov 29 2006

STATUS

approved

editing

#5 by Russ Cox at Fri Mar 30 18:40:03 EDT 2012

AUTHOR

_Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), _, Aug 06 2006

Discussion

Fri Mar 30

18:40

OEIS Server: https://oeis.org/edit/global/226

#4 by Russ Cox at Fri Mar 30 17:28:19 EDT 2012

EXTENSIONS

Incorrect comment removed by _Charles R Greathouse IV (charles.greathouse(AT)case.edu), _, Mar 25 2010

Discussion

Fri Mar 30

17:28

OEIS Server: https://oeis.org/edit/global/147

#3 by N. J. A. Sloane at Tue Jun 01 03:00:00 EDT 2010

PROG

(PARI) v=[1]; for(n=1, 2, 134, if(ispower(numdiv(n)), v=concat(v, n))); v (Hobson)

KEYWORD

easy,nonn,new

EXTENSIONS

Incorrect comment removed by Charles R Greathouse IV (charles.greathouse(AT)case.edu), Mar 25 2010

#2 by N. J. A. Sloane at Wed Dec 06 03:00:00 EST 2006

DATA

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

PROG

(PARI) v=[1]; for(n=1, 134, if(ispower(numdiv(n)), v=concat(v, n))); v (Hobson)

EXTENSIONS

More terms from Nick Hobson Nov 29 2006

#1 by N. J. A. Sloane at Fri Sep 29 03:00:00 EDT 2006

NAME

Natural numbers n with number of divisors equal to a perfect power.

DATA

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

OFFSET

1,2

KEYWORD

easy,nonn

AUTHOR

Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Aug 06 2006

STATUS

approved