Fwd: updating riesel prime exponent lists
Maximilian Hasler
maximilian.hasler at gmail.com
Fri May 4 15:42:16 CEST 2007
Dear seqfans,
following Neil's suggestion, I forward you the following message.
Best regards,
M.H.
PS: Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime:
http://www.research.att.com/~njas/sequences/Sindx_Pri.html#riesel
Dear Neil,
I just started submitting "comments" to extend lists of n such that
k*2^n +/- 1 is prime,
using
http://www.prothsearch.net/riesel.html
and
http://www.prothsearch.net/riesel2.html
I started with some of the most interesting (= shortest) lists,
but I noticed that there are many....
Also, maybe someone working on that would merit having his name there
better than me.
Maximilian
FYI, I'm about 1/3 of the way through my duplicates file, so there will
probably be around 40 or 50 more of these emails.
Straightforward duplicates:
A113743 and A112559
A056254 and A101836
A004611 and A121057
A083966 and A092115
A108162 and A108173
A067505 and A067512
A085942 and A113601
A074148 and A100797
Possible duplicates:
A003555 and A099639
A073570 and A116964
A067816 and A076629
A051538 and A119635
A098019 and A098020
Is there a syntax to query the database for more than one sequence by a
number (I've tried comma, space, and semicolon separation, using two "id:"
entries separated by spaces, etc.)? For instance, if I want to look at
A028284 and A066948 on the same results page. It would be nice to format my
duplicate submissions using this syntax so those checking the possible dupes
can bring them up on one screen, instead of having to copy, paste, and then
my suggestion would be space-separated "id:" lists (similar to what you can
do with "keyword:"); "id:A028284 id:A066948 ...".
There is some confusion with this sequence. (below)
By the comment there are odd terms in this sequence: 1, 351, 375, 381, 471
But the comments by Adamchuk imply that all the terms are even.
Should we create an even subsequence of this sequence. Are the comments correct?
Tanya
A074202 Numbers n such that the number of 1's in the binary representation of n divides 2^n-1.
COMMENT
Odd terms are in A074203.
Also a(n) = 2*A000069[n-2] for n>1, where A000069[n] are the odious numbers: odd number of 1's in binary expansion. - Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 15 2006
FORMULA
a(n) = 4n - 7 + (-1)^A000120[n-2] for n>1. - Alexander Adamchuk (alex(AT)kolmogorov.com), Sep 15 2006
CROSSREFS
Cf. A000120, A000069.
Benoit Cloitre (abmt(AT)wanadoo.fr), Sep 17 2002
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