The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A091880

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A091880

A049232 indexed by A000040.
(history; published version)

#15 by Michel Marcus at Mon Aug 26 02:00:29 EDT 2024

STATUS

reviewed

approved

#14 by Joerg Arndt at Mon Aug 26 01:19:04 EDT 2024

STATUS

proposed

reviewed

#13 by Jason Yuen at Sun Aug 25 23:10:50 EDT 2024

STATUS

editing

proposed

#12 by Jason Yuen at Sun Aug 25 23:10:47 EDT 2024

COMMENTS

The asymptotic density of this sequence is 1 - 2 * Product_{p prime} (1-1/(p*(p-1)) ) = 1 - 2 * A005596 = 0.252088... - Amiram Eldar, Feb 28 2021

STATUS

approved

editing

#11 by Michel Marcus at Sun Feb 28 03:09:02 EST 2021

STATUS

reviewed

approved

#10 by Joerg Arndt at Sun Feb 28 02:44:40 EST 2021

STATUS

proposed

reviewed

#9 by Amiram Eldar at Sun Feb 28 01:57:52 EST 2021

STATUS

editing

proposed

#8 by Amiram Eldar at Sun Feb 28 01:44:28 EST 2021

COMMENTS

The asymptotic density of this sequence is 1 - 2 * Product_{p prime} (1-1/(p*(p-1)) = 1 - 2 * A005596 = 0.252088... - Amiram Eldar, Feb 28 2021

#7 by Amiram Eldar at Sun Feb 28 01:44:01 EST 2021

LINKS

Amiram Eldar, <a href="/A091880/b091880.txt">Table of n, a(n) for n = 1..10000</a>

FORMULA

a(n) = k such that A000040(k) = A049232(n).

CROSSREFS

Cf. A000040, A005596, A049232.

#6 by Amiram Eldar at Sun Feb 28 01:43:05 EST 2021

MATHEMATICA

(*in Mathematica6*)Select[Range[100], ! SquareFreeQ[Prime[ # ] + 2] &] [From _(* _Zak Seidov_, Oct 28 2008] *)

STATUS

approved

editing