mersenneforum.org Looking for a list of all untouchable numbers less than 1000000
 Register FAQ Search Today's Posts Mark Forums Read

 2018-04-22, 22:35 #1 Stargate38     "Daniel Jackson" May 2011 14285714285714285714 12458 Posts Looking for a list of all untouchable numbers less than 1000000 I've been looking everywhere, and I've only found the OEIS entry (A005114), which stops at 60000. Where can I find a list of all the untouchable numbers less than 106?
 2018-04-23, 08:08 #2 AndrewWalker     Mar 2015 Australia 2·41 Posts The Giovanni Resta link on the OEIS page apparently has up to 10^6, haven't looked at any of the others.
 2018-04-23, 11:10 #3 henryzz Just call me Henry     "David" Sep 2007 Cambridge (GMT/BST) 3·1,979 Posts http://mersenneforum.org/showthread.php?t=21586 is quite relevant
 2018-04-23, 19:58 #4 garambois     "Garambois Jean-Luc" Oct 2011 France 12548 Posts Unless I misunderstand your request, I probably have what you are looking for up to 500 000 000 on this page of my website. Untouchable numbers are all even numbers except for 5. So you can download "number of aliquot antecedents of the even numbers from 0 to 500 000 000".
 2018-04-23, 20:01 #5 garambois     "Garambois Jean-Luc" Oct 2011 France 22×32×19 Posts Sorry, I forgot the link of the page : http://www.aliquotes.com/aliquote_base.htm
 2021-08-18, 04:27 #6 sweety439     "99(4^34019)99 palind" Nov 2016 (P^81993)SZ base 36 311510 Posts To check whether a number n>1 is untouchable, checking to (n-1)^2 is enough, if no k<=(n-1)^2 is found that sigma(k)-k = n, then n is untouchable.

 Similar Threads Thread Thread Starter Forum Replies Last Post cardmaker Msieve 6 2017-01-30 23:58 imo PrimeNet 7 2007-05-16 11:29 hymie Lone Mersenne Hunters 3 2005-09-03 05:49 Neves Math 3 2004-01-29 16:21 Ice9 Math 9 2004-01-27 16:32

All times are UTC. The time now is 13:06.

Thu Dec 2 13:06:19 UTC 2021 up 132 days, 7:35, 0 users, load averages: 1.86, 1.47, 1.30