OFFSET
1,1
COMMENTS
The smaller prime factor of the 125-digit semiprime 2^413 - 413^2 has 40 digits; for the 127-digit semiprime 2^421 - 421^2 the smaller prime factor has 45 digits. The next term is >= 583. - Hugo Pfoertner, Oct 14 2007
The factorization of the 176-decimal-digit composite 2^583 - 583^2 using SNFS in YAFU took 55000 seconds on 4 cores of an i5-2400 CPU @ 3.10GHz. a(38) >= 617. - Hugo Pfoertner, Jul 23 2019
a(41) >= 827. - Hugo Pfoertner, Jul 26 2019
LINKS
Dario Alpern, Factorization using the Elliptic Curve Method.
factordb, Status of 2^583-583^2 in factordb.com.
factordb, Status of 2^617-617^2 in factordb.com.
factordb, Status of 2^827-827^2 in factordb.com.
EXAMPLE
a(1) = 11 because 2^11 - 11^2 = 1927 = 41*47.
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Hugo Pfoertner, Oct 18 2004
EXTENSIONS
More terms from Hugo Pfoertner, Oct 14 2007
a(37)-a(40) from Hugo Pfoertner, Jul 26 2019
STATUS
approved