The On-Line Encyclopedia of Integer Sequences (OEIS)

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A074594

Number of distinct prime factors of numbers that are not prime powers.
(history; published version)

#7 by Harvey P. Dale at Sun Nov 18 09:10:25 EST 2018

STATUS

editing

approved

#6 by Harvey P. Dale at Sun Nov 18 09:10:21 EST 2018

LINKS

Harvey P. Dale, <a href="/A074594/b074594.txt">Table of n, a(n) for n = 1..1000</a>

STATUS

approved

editing

#5 by Harvey P. Dale at Sun Nov 18 09:09:02 EST 2018

STATUS

editing

approved

#4 by Harvey P. Dale at Sun Nov 18 09:08:59 EST 2018

MATHEMATICA

PrimeNu/@Select[Range[2, 300], !PrimePowerQ[#]&] (* Harvey P. Dale, Nov 18 2018 *)

STATUS

approved

editing

#3 by Russ Cox at Fri Mar 30 18:50:25 EDT 2012

AUTHOR

_Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), _, Aug 25 2002

Discussion

Fri Mar 30

18:50

OEIS Server: https://oeis.org/edit/global/246

#2 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009

KEYWORD

nonn,new

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystemsgmail.com), Aug 25 2002

#1 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

NAME

Number of distinct prime factors of numbers that are not prime powers.

DATA

2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 3, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 3, 3, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 3, 2

OFFSET

1,1

FORMULA

a(n) = A001221(A024619(n)).

CROSSREFS

Cf. A074595, A074592, A074593.

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), Aug 25 2002

STATUS

approved