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 A178889 #16 Nov 26 2015 05:49:28 %S A178889 19,21,29,31,32,39,41,42,43,49,51,52,53,54,59,61,62,63,64,65,69,71,72, %T A178889 73,74,75,76,79,81,82,83,84,85,86,87,89,91,92,93,94,95,96,97,98,99, %U A178889 101,110,111,119,120,121,130,131,140,141,150,151,160,161,170,171,180,181 %N A178889 Numbers n such that R(n) (n-reversed) appears to the left of n in the string 12345678910111213.... %C A178889 Consider the infinite string of digits A007908(row->infinity). Whenever the digit-reversed variant of n, R(n) = A004086(n), appears ahead of n in that string, adjoin n to the current sequence. %e A178889 19 is generated where 9 meets 10, 12345678(91)01112131415161718(19)20... %e A178889 21 is generated by 1 and 2: (12)34567891011121314151617181920(21)22... %e A178889 29 is generated where 19 joins 20: 1234567891011121314151617181(92)02122232425262728(29)30... %Y A178889 Cf. A116700. %K A178889 nonn,base,easy %O A178889 1,1 %A A178889 _Paolo P. Lava_ & _Giorgio Balzarotti_, Jun 21 2010 %E A178889 Definition shortened, examples detailed, keyword:base added by _R. J. Mathar_, Jul 13 2010