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 A124097 #6 Mar 31 2012 20:24:56 %S A124097 0,1,2,3,4,5,6,7,8,9,11,12,14,15,21,22,23,24,25,26,32,33,35,36,41,42, %T A124097 44,45,47,48,51,52,53,54,55,56,57,58,59,62,63,65,66,68,69,70,74,75,77, %U A124097 78,80,84,85,86,87,88,89,90,95,96,98,99,111,112,114,115,121,122,123,124 %N A124097 Numbers which are "easy" to key on a standard telephone keypad. %C A124097 On a standard telephone keypad, i.e. 123 | 456 | 789 | 0, a number is "easy" to key in if each adjacent pair of digits in the number are the same, or are adjacent - either horizontally or vertically or diagonally. For example, adjacent to the 2 key are 1 and 3 (horizontal), 5 (vertical) and 4 and 6 (diagonal) so any of these digits could come after a 2 (but not 7, 8, 9 or 0). %H A124097 N. J. A. Sloane, <a href="/A124097/b124097.txt">Table of n, a(n) for n = 1..10001</a> %e A124097 126 is a term since the 1 and 2 keys are adjacent and the 6 is diagonally adjacent to the 2. %K A124097 nonn,dumb,base %O A124097 1,3 %A A124097 _Paul Richards_, Dec 12 2006