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 A369347 #8 Jan 24 2024 08:01:21
%S A369347 11,22,33,44,55,66,77,88,99,111,222,333,444,555,666,777,888,999,1010,
%T A369347 1111,1212,1313,1414,1515,1616,1717,1818,1919,2020,2121,2222,2323,
%U A369347 2424,2525,2626,2727,2828,2929,3030,3131,3232,3333,3434,3535,3636,3737,3838,3939
%N A369347 Numbers whose decimal expansion is quasiperiodic.
%C A369347 The decimal representation of a term (ignoring leading zeros) can be covered by (possibly overlapping) occurrences of one of its proper prefixes.
%C A369347 This sequence contains, among others, A020338 and A239019.
%C A369347 The first term that does not belong to A239019 is a(109) = 10101.
%H A369347 <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a>
%e A369347 The number 10101101 belongs to this sequence as its decimal expansion can be covered by copies of its proper prefix 101:
%e A369347 101
%e A369347 101
%e A369347 101
%e A369347 ........
%e A369347 10101101
%o A369347 (PARI) is(w) = { my (tt=0); for (l=1, oo, my (t=w%(10^l)); if (t!=tt, if (t==w, return (0)); my (r=w, g=l); while (g-->=0 && r>=t, r \= 10; if (r%(10^l)==t, if (r==t, return (1), g=l))); tt = t)) }
%Y A369347 Cf. A020338, A239019, A320441 (binary analog).
%K A369347 nonn,base
%O A369347 1,1
%A A369347 _Rémy Sigrist_, Jan 21 2024