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 A094534 #17 Jun 22 2018 02:48:40
%S A094534 1,7,17,51,67,167,251,417,501,667,751,917,1251,1667,5001,5417,6251,
%T A094534 6667,10417,16667,50001,56251,60417,66667,166667,260417,406251,500001,
%U A094534 666667,760417,906251,1406251,1666667,5000001,5260417,6406251,6666667,16666667
%N A094534 Centered hexamorphic numbers: the k-th centered hexagonal number, 3k(k-1)+1, ends in k.
%C A094534 Given any number in the sequence, if you remove one or more digits from the beginning you always get another number in the sequence. This makes it easy to find higher terms -- just take an existing term and try adding a digit (with perhaps additional 0's) at the beginning. For example, to 6251 prepend 5 to get a 5-digit term, or 40 or 90 to get a 6-digit term.
%H A094534 Robert Munafo, <a href="http://www.mrob.com/pub/math/seq-a094534.html">Sequence A094534, Centered Hexamorphic, or Automorphic Hexagonal, Numbers</a>
%H A094534 Cliff Pickover, <a href="http://sprott.physics.wisc.edu/pickover/clifft.html">Centered Hexamorphic Numbers</a>.
%F A094534 10^(d-1) <= n < 10^d; 3n(n-1)+1 == n mod 10^d
%e A094534 417 is in the sequence because if n=417, 3n(n-1)+1=520417, which ends in 417.
%o A094534 (PARI) isok(n) = {my(m = 3*n*(n-1)+1); (m - n) % 10^#Str(n) == 0; } \\ _Michel Marcus_, Jun 21 2018
%Y A094534 Cf. A003215, A003226.
%K A094534 base,easy,nonn
%O A094534 1,2
%A A094534 _Robert Munafo_, May 07 2004
%E A094534 Name changed by _Robert Dawson_, Jun 20 2018