Brent, Richard PCrandall, Richard EDilcher, Karl2003-07-072004-05-192011-01-052004-05-192011-01-051997http://hdl.handle.net/1885/40753http://digitalcollections.anu.edu.au/handle/1885/40753We report the discovery of new 27-decimal digit factors of the thirteenth and sixteenth Fermat numbers. Each of the new factors was found by the elliptic curve method. After division by the new factors and other known factors, the quotients are seen to be composite numbers with 2391 and 19694 decimal digits respectively.218070 bytes356 bytesapplication/pdfapplication/octet-streamen-AUFermat numberselliptic curve methodTR-CS1997