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 A307256 #17 Apr 10 2019 22:29:03
%S A307256 0,1,2,3,4,124343,124401,132114,10032011,20122404,30213311,40304213,
%T A307256 1333204002110,1411043040042,101232041210022,203110224214344,
%U A307256 210011311131122,304342321033141,311243402442011,311300321024140,413122042420324,420023124324311,14233443213321013401
%N A307256 Numbers k such that k is the substring identical to the most significant digits of its base-5 representation.
%C A307256 Numbers k whose base-5 representation begins with the same digits as k itself.
%H A307256 Scott R. Shannon, <a href="/A307256/b307256.txt">Table of n, a(n) for n = 1..500</a>
%e A307256 132114_10 = 13211424_5, which also begins with '132114'.
%t A307256 With[{b = 5}, Select[Array[{FromDigits@ #, #} &@ IntegerDigits[#, b] &, b^10, 0], Take[IntegerDigits[First@ #, b], Length@ Last@ #] == Last[#] &][[All, 1]]] (* _Michael De Vlieger_, Apr 01 2019 *)
%Y A307256 This is a subsequence of A038105.
%K A307256 nonn,base
%O A307256 1,3
%A A307256 _Scott R. Shannon_, Apr 01 2019