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 A261924 #11 Dec 06 2015 18:16:15 %S A261924 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,22,33,44,55,66,77,88, %T A261924 99,110,121,132,143,154,165,176,187,198,202,212,222,232,242,252,262, %U A261924 272,282,292,302,303,312,313,322,323,332,333,342,343,352,353,362,363,372,373,382,383,393 %N A261924 Numbers that are the sum of two palindromes of the same length. %C A261924 Theorem: For a fixed value of d, adding two palindromes of length d in all possible ways produces 19 distinct sums if d=1, and 17*19^floor((d-1)/2) distinct sums if d>1. (The number of palindromes with d digits is 10 if d = 1, otherwise 9*10^floor((d-1)/2).) - _N. J. A. Sloane_, Dec 06 2015 %H A261924 N. J. A. Sloane, <a href="/A261924/b261924.txt">Table of n, a(n) for n = 1..12956</a> %Y A261924 Cf. A002113, A261921, A261925, etc. %K A261924 nonn,base %O A261924 1,3 %A A261924 _David Applegate_ and _N. J. A. Sloane_, Sep 17 2015 %E A261924 Modified to include the zero palindrome. - _N. J. A. Sloane_, Dec 06 2015