OFFSET
1,1
COMMENTS
All prime divisors of (R^13 - 1)/(R - 1) different from 13 are congruent to 1 modulo 26.
REFERENCES
M. Ram Murty, Problems in Analytic Number Theory, Springer-Verlag, NY, (2001), pp. 208-209.
EXAMPLE
a(2) = 11462027512399586179504472990060461 is the smallest prime divisor congruent to 1 mod 26 of (R^13 - 1)/(R - 1) = 11462027512399586179504472990060461, where Q = 53 and R = 13*Q.
MATHEMATICA
a={53}; q=1;
For[n=2, n<=5, n++,
q=q*Last[a]; r=13*q;
AppendTo[a, Min[Select[FactorInteger[(r^13-1)/(r-1)][[All, 1]], Mod[#, 26]==1 &]]];
];
a (* Robert Price, Jul 16 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Nick Hobson, Nov 18 2006
EXTENSIONS
More terms from Sean A. Irvine, Jun 24 2011
STATUS
approved