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 A007284 M4477 #29 Jul 08 2025 17:03:26
%S A007284 0,1,3,8,10,11,13,18,30,31,33,38,80,81,83,88,100,101,103,108,110,111,
%T A007284 113,118,130,131,133,138,180,181,183,188,300,301,303,308,310,311,313,
%U A007284 318,330,331,333,338,380,381,383,388,800,801,803,808,810,811,813,818
%N A007284 Horizontally symmetric numbers.
%D A007284 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A007284 Indranil Ghosh, <a href="/A007284/b007284.txt">Table of n, a(n) for n = 0..50000</a>
%F A007284 Numbers using only digits 0, 1, 3 and 8.
%o A007284 (Python)
%o A007284 allowed = ("0", "1", "3", "8")
%o A007284 def a(n):
%o A007284 return all(x in allowed for x in str(n))
%o A007284 print([i for i in range(50000) if a(i)])
%o A007284 # _Indranil Ghosh_, Feb 03 2017
%Y A007284 Cf. A046031.
%K A007284 nonn,easy,base
%O A007284 0,3
%A A007284 _N. J. A. Sloane_
%E A007284 More terms from _Henry Bottomley_, Feb 14 2000