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 A083142 #8 Dec 02 2015 00:37:27 %S A083142 919,9119,90109,91019,91119,91219,91319,91419,91519,91619,91719,91819, %T A083142 91919,92129,93139,94149,95159,96169,97179,98189,99199,901109,910019, %U A083142 911119,912219,913319,914419,915519,916619,917719,918819,919919,921129 %N A083142 Palindromes that cannot be expressed as the difference of two palindromes. %C A083142 Palindromes in A084843. All terms begin with 9. Do all terms contain a 1? %e A083142 9 is not a member because 9 = 11 - 2. %Y A083142 Cf. A002113, A084843. %K A083142 base,easy,nonn %O A083142 1,1 %A A083142 _Amarnath Murthy_ and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Apr 25 2003 %E A083142 Edited and extended by _David Wasserman_, Oct 19 2004