OFFSET
1,1
COMMENTS
Up to now only two primes p such that p^2 divide 2^(p-1)-1 are known (these two are Wieferich primes, see A001220).
The sequence is finite with A001222(2^1092-1) = 49 terms; A001221(2^1092-1) = 45. - Reinhard Zumkeller, May 14 2010
Terms appearing more than once (in fact twice) are 3, 7, 13, and 1093.
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..49 (complete sequence)
Dario A. Alpern, Factorization using the Elliptic Curve Method.
CROSSREFS
KEYWORD
fini,full,nonn
AUTHOR
Artur Jasinski, Jan 30 2010
EXTENSIONS
Missing terms a(34) and a(35) inserted by Reinhard Zumkeller, May 14 2010
Definition clarified and terms corrected by Joerg Arndt, Apr 25 2011
STATUS
approved