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 A249182 #13 Dec 10 2015 02:22:15
%S A249182 1,2,3,6,9,8,7,4,12,23,36,69,98,87,74,41,123,236,369,698,987,874,741,
%T A249182 412,1236,2369,3698,6987,9874,8741,7412,4123,12369,23698,36987,69874,
%U A249182 98741,87412,74123,41236,123698,236987,369874,698741,987412,874123,741236,412369
%N A249182 Proceed counterclockwise on the outer keys of a numeric keypad (i.e., 1,2,3,6,9,8,7,4): first single digits, then concatenate two digits, then three, etc.
%C A249182 k-digit terms start at index 8k-7; for example, at index 57, start the 8-digit terms 12369874, 23698741, 36987412, 69874123, 98741236, 87412369, 74123698, 41236987.
%o A249182 (PARI) d=Vec("12369874");for(L=1,6,for(i=1,#d,print1(concat(vector(L,j,d[(i+j-2)%#d+1]))",")))
%Y A249182 Cf. A059805, A091331, A091332, A249163.
%K A249182 nonn,base
%O A249182 1,2
%A A249182 _M. F. Hasler_, Oct 23 2014