OFFSET
1,1
COMMENTS
Subsequence of A060443.
Prime factors of composite Mersenne numbers; A089162 with the Mersenne primes A000668 removed. - Jens Kruse Andersen, Jul 11 2014
LINKS
Jens Kruse Andersen, Table of n, a(n) for n = 1..577
Sergey Nikitin, Euler-Fermat algorithm and some of its applications, 2018.
Sam Wagstaff, The Cunningham Project
EXAMPLE
A054723(1) = 11. 2^11-1 = 2047 = 23*89. - Jens Kruse Andersen, Jul 11 2014
Triangle begins:
23, 89;
47, 178481;
233, 1103, 2089;
223, 616318177;
13367, 164511353;
431, 9719, 2099863;
2351, 4513, 13264529;
6361, 69431, 20394401;
MATHEMATICA
Map[FactorInteger, Select[2^Prime@Range@20 - 1, CompositeQ]][[All, All, 1]] // Flatten (* Michael De Vlieger, Nov 20 2018 *)
PROG
(PARI) forprime(n=1, 100, m=2^n-1; if(!isprime(m), f=factor(m); for(i=1, #f~, print1(f[i, 1]", ")))) \\ Jens Kruse Andersen, Jul 11 2014
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Felix Fröhlich, Jun 28 2014
STATUS
approved