|
Search: id:A140803
|
|
|
| A140803 |
|
Numbers of the form 2^(pq)-1/((2^p-1)(2^q-1)), where p>q are primes. |
|
+0
2
|
|
| 3, 11, 43, 151, 683, 2359, 2731, 43691, 174763, 599479, 2796203, 8727391, 9588151, 178956971, 715827883, 2454285751
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
The sequence contains, in particular, A126614 (q=2)and A143012 (q=3).
If pq-1 is squarefree then the terms of the sequence are either primes or overpseudoprimes to base 2 (see A141232). In particular, they are strong pseudoprimes to base 2 (A001262).
|
|
REFERENCES
|
V. Shevelev, Process of "primoverization" of numbers of the form a^n-1, http://arxiv.org/abs/0807.2332
|
|
CROSSREFS
|
Cf. A001262 A141232 A126614 A143012.
Sequence in context: A118166 A106876 A034477 this_sequence A084643 A007583 A026671
Adjacent sequences: A140800 A140801 A140802 this_sequence A140804 A140805 A140806
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladimir Shevelev (shevelev(AT)bgu.ac.il), Jul 15 2008, Jul 22 2008; corrected Sep 07 2008
|
|
|
Search completed in 0.002 seconds
|
