A093109 - OEIS

A093109

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

2, 4, 6, 8, 16, 18, 32, 42, 52, 54, 55, 64, 93, 128, 162, 171, 256, 272, 294, 355, 406, 486, 506, 512, 605, 676, 820, 1024, 1332, 1458, 1474, 1711, 1806, 1830, 2048, 2058, 2162, 2504, 2525, 2715, 2756, 2883, 2943, 3081, 3249, 3629, 3916, 4096, 4374, 4624, 5210

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

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.

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

LINKS

Table of n, a(n) for n=1..51.

MATHEMATICA

Select[Range[10000], GCD[#, Cyclotomic[#, 5]]!=1 &] (* Emmanuel Vantieghem, Nov 13 2016 *)

CROSSREFS

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

Sequence in context: A133808 A160560 A332291 * A070034 A329798 A364814

Adjacent sequences: A093106 A093107 A093108 * A093110 A093111 A093112

KEYWORD

nonn

AUTHOR

Ralf Stephan, Mar 20 2004

EXTENSIONS

More terms from Vladeta Jovovic, Apr 02 2004

Definition corrected by Jerry Metzger, Nov 04 2009

STATUS

approved