A093109 - OEIS

%I #23 Oct 24 2017 02:27:54

%S 2,4,6,8,16,18,32,42,52,54,55,64,93,128,162,171,256,272,294,355,406,

%T 486,506,512,605,676,820,1024,1332,1458,1474,1711,1806,1830,2048,2058,

%U 2162,2504,2525,2715,2756,2883,2943,3081,3249,3629,3916,4096,4374,4624,5210

%N Numbers n such that the Zsigmondy number Zs(n,5,1) differs from the n-th cyclotomic polynomial evaluated at 5.

%C Numbers n such that A019323(n) does not equal A064081(n).

%C _Vladeta Jovovic_ points out that the sequence seems to contain the powers of two as well as the numbers of the form 2*3^k.

%C Numbers of the form ord(5,p)*p^k where prime p <> 5 and k > 0. Also numbers n > 0 such that A019323(n) =/= 1 (mod n). Also A019323(n) mod n = gcd(n, A019323(n)) = p. - _Thomas Ordowski_, Oct 22 2017

%t Select[Range[10000], GCD[#, Cyclotomic[#, 5]]!=1 &] (* _Emmanuel Vantieghem_, Nov 13 2016 *)

%Y Cf. A093106, A093107, A093108, A019323, A064081.

%K nonn

%O 1,1

%A _Ralf Stephan_, Mar 20 2004

%E More terms from _Vladeta Jovovic_, Apr 02 2004

%E Definition corrected by _Jerry Metzger_, Nov 04 2009