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 A084043 #5 Dec 05 2013 19:56:16 %S A084043 111,222,333,444,555,666,777,888,999,0,1111,82128,41314,414414,55155, %T A084043 61616,317713,41814,41914,0,912219,2222,52325,2324232,52525,82628, %U A084043 82728,828828,52925,0,2131312,23232,3333,2243422,535535,2136312,43734,88388 %N A084043 Smallest palindromic multiple of n in which the digit string of n appears as sandwiched between at least a pair of digits, or 0 if n = 10k or no such number exists. %C A084043 Conjecture: a(n) = 0 iff n = 10k. %K A084043 base,nonn %O A084043 1,1 %A A084043 _Amarnath Murthy_, May 26 2003 %E A084043 Corrected and extended by _Ray Chandler_, Jun 11 2003