The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A297401

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

A297401

Non-sphenic numbers with exactly 8 divisors.
(history; published version)

#49 by Charles R Greathouse IV at Mon Apr 03 10:36:13 EDT 2023

LINKS

Caldwell and Honaker, <a href="httphttps://primes.utmt5k.eduorg/curios/page.php?curio_id=31757">Prime Curios!</a>

Discussion

Mon Apr 03

10:36

OEIS Server: https://oeis.org/edit/global/2966

#48 by Peter Luschny at Thu Jan 04 06:33:40 EST 2018

STATUS

reviewed

approved

#47 by Joerg Arndt at Thu Jan 04 04:08:17 EST 2018

STATUS

proposed

reviewed

#46 by Robert Israel at Sun Dec 31 19:15:37 EST 2017

STATUS

editing

proposed

#45 by Robert Israel at Sun Dec 31 19:15:28 EST 2017

LINKS

Robert Israel, <a href="/A297401/b297401.txt">Table of n, a(n) for n = 1..10000</a>

#44 by Robert Israel at Sun Dec 31 19:13:58 EST 2017

MAPLE

N:= 1000: # to get all terms <= N

P:= select(isprime, [2, seq(i, i=3..N)]):

R:= NULL:

for p in P do

if p^7 <= N then R:= R, p^7 fi;

if p^3 > N then break fi;

for q in P while p^3*q <= N do if q <> p then R:= R, p^3*q fi od:

od:

sort([R]); # Robert Israel, Dec 31 2017

STATUS

proposed

editing

#43 by Michel Marcus at Sun Dec 31 05:54:21 EST 2017

STATUS

editing

proposed

#42 by Michel Marcus at Sun Dec 31 05:53:59 EST 2017

COMMENTS

These are the numbers of the form p^3*q (with primes p and q distinct) or p^7. Thus it is the union of A065036 and A092759, and this can be used for direct enumeration. _- _Alex Meiburg_, Dec 31 2017

STATUS

proposed

editing

#41 by Alex Meiburg at Sun Dec 31 05:44:11 EST 2017

STATUS

editing

proposed

#40 by Alex Meiburg at Sun Dec 31 05:43:18 EST 2017

COMMENTS

These are the numbers of the form p^3*q (with primes p and q distinct) or p^7. Thus it is the union of A065036 and A092759, and this can be used for direct enumeration. _Alex Meiburg_, Dec 31 2017

CROSSREFS

The complement Subsequence of A007304 in A030626.

The union of A065036 and A092759.

Cf. A000005, A030626, A065036, A092759.

STATUS

proposed

editing