A067937 - OEIS

%I #12 May 21 2022 08:42:16

%S 1,2,4,5,8,10,16,20,22,25,28,37,40,44,50,52,68,70,76,80,88,92,100,110,

%T 112,116,124,125,130,148,154,164,172,176,188,200,208,212,220,236,244,

%U 250,268,280,284,286,292,316,332,340,356,364,370,388,400,404,412,418

%N Let rep(k) be the k-th repunit number, sequence gives values of k such that rep(k) == rep(4) (mod k).

%H Amiram Eldar, <a href="/A067937/b067937.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[500],Mod[FromDigits[PadRight[{},#,1]],#]==Mod[1111,#]&] (* _Harvey P. Dale_, Nov 12 2015 *)

%Y Cf. A002275.

%K easy,nonn

%O 1,2

%A _Benoit Cloitre_, Mar 05 2002