A247230 - OEIS

%I #12 Dec 14 2014 15:11:25

%S 3,13,71,55987,12207031,16148168401,50544702849929377,

%T 109912203092239643840221,26552618219228090162977481,

%U 582595509837473004489665028935473297399,568972471024107865287021434301977158534824481,4673016293261684390446904937094157950067612234753

%N Maximum of the greatest prime factors of (i^prime(n)-1)/(i-1), when i runs through all integers in [2, prime(n)].

%C If in the definition "maximum" is replaced with "minimum," then we obtain A247229.

%F a(n)==1 (mod prime(n)).

%o (PARI) a(n) = {maxi = 0; p = prime(n); for (i=2, p, f = factor((i^p-1)/(i-1)); gpf = f[#f~, 1]; if (! maxi, maxi = gpf, maxi = max(maxi, gpf));); maxi;} \\ _Michel Marcus_, Dec 09 2014

%Y Cf. A247216, A247229.

%K nonn

%O 1,1

%A _Vladimir Shevelev_, Nov 27 2014

%E More terms from _Peter J. C. Moses_, Nov 27 2014