This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A232769 #31 Jul 19 2016 11:39:39
%S A232769 1,3,111,4107,151959,5622483,22494039,208031871,225121209,832279443,
%T A232769 7697179227,8329484733,27486820443,30794339391,92366302683,
%U A232769 123199851603,230915528769,284795631399,308190935121,1017012356391
%N A232769 Numbers n not divisible by 9 such that n divides 10^n - 1 (A014950).
%C A232769 The above terms reduced modulo 9 yield: 1, 3, 3, 3, 3, 3, 6, 3, 6, 6, 3, 6, 3, 6, 3, 3, 3, 3, 6, 3, 6, …, .
%C A232769 The only primes less than a billion which can divide members of this sequence are 3, 37, 5477, 607837, 1519591, 2028119, 15195911, 18235093, 44988079, 74202397, 247629013, 337349203, 395397319, 462411133, and 674699071. - _Charles R Greathouse IV_, Dec 03 2013
%H A232769 Ray Chandler, <a href="/A232769/b232769.txt">Table of n, a(n) for n = 1..55</a>
%t A232769 k = 3; lst = {1}; While[k < 10^10 + 1, If[ PowerMod[10, k, k] == 1, AppendTo[ lst, k]; Print@ k]; k += 3; If[ PowerMod[ 10, k, k] == 1, AppendTo[ lst, k]; Print@ k]; k += 6]; lst
%o A232769 (PARI) is(n)=n%9 && Mod(10,n)^n==1 \\ _Charles R Greathouse IV_, Dec 03 2013
%o A232769 (PARI) forstep(n=1,1e8,[2, 4, 4, 2, 4, 2, 2, 2, 6, 2, 2, 4, 2, 2, 2, 4, 2, 2, 2, 4, 2, 2, 6, 2, 2, 2, 4, 2, 4, 4, 2, 2], if(Mod(10,n)^n==1,print1(n", "))) \\ _Charles R Greathouse IV_, Dec 03 2013
%Y A232769 Cf. A014950.
%K A232769 nonn
%O A232769 1,2
%A A232769 _Hans Havermann_ and _Robert G. Wilson v_, Nov 29 2013
%E A232769 a(22)-a(26) from _Ray Chandler_, Dec 11 2013
%E A232769 B-file extended through a(55) by _Ray Chandler_, Dec 24 2013