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 A077573 #9 Jul 24 2025 19:06:22
%S A077573 0,111,0,111111,11,111111,1111111111111111,111111111111111111,
%T A077573 1111111111111111111111,1111111111111111111111111111,111111111111111,
%U A077573 111,11111,111111111111111111111,1111111111111111111111111111111111111111111111
%N A077573 Smallest number of the form (10^k -1)/9 == 0 (mod prime(n)). with a(1) = a(3) = 0.
%C A077573 For every prime p > 5, {10^(p-1) -1}/9 == 0 (mod p), by Fermat's Little theorem.
%D A077573 Amarnath Murthy, On the divisors of Smarandache Unary Sequence. Smarandache Notions Journal, Vol. 11, 2000.
%H A077573 Alois P. Heinz, <a href="/A077573/b077573.txt">Table of n, a(n) for n = 1..170</a>
%Y A077573 Cf. A071126.
%K A077573 nonn
%O A077573 1,2
%A A077573 _Amarnath Murthy_, Nov 11 2002
%E A077573 More terms from _Sascha Kurz_, Jan 04 2003