OFFSET

1,2

COMMENTS

Subsequence of A014949.

a(5) = 299593 = (8^7-1)/7 is a repunit in base 8, 1111111(base 8). The first 5 listed terms of a(n) are terms of the finite sequence A003530: divisors of 8^7-1. [Corrected and edited by M. F. Hasler, Nov 21 2018]

Also a subsequence of A177908, see there for more comments on properties of terms of this sequence. - M. F. Hasler, Nov 21 2018

MATHEMATICA

Select[Range[20000], IntegerQ[(PowerMod[8, #, #^2 ]-1)/#^2 ]&]

PROG

(PARI) is(n)=Mod(8, n^2)^n==1 \\ M. F. Hasler, Nov 21 2018

CROSSREFS

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Jan 05 2007, Jan 07 2007

EXTENSIONS

More terms from Ryan Propper, Jan 05 2007

Terms a(12) onward from Max Alekseyev, May 06 2010

STATUS

approved