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 A265513 #4 Dec 09 2015 20:17:32 %S A265513 0,1,2,3,0,5,5,5,0,5,10,10,0,5,10,15,0,17,17,17,0,21,21,21,0,25,25,25, %T A265513 0,29,29,29,0,17,34,34,0,21,38,38,0,25,42,42,0,29,46,46,0,17,34,51,0, %U A265513 21,38,55,0,25,42,59,0,29,46,63,0,65,65,65,0,65,65,65,0,65,65,65,0,65,65,65,0,65,65,65,0,85,85 %N A265513 a(n) = largest base-4 palindrome m <= n such that every base-4 digit of m is <= the corresponding digit of n; m is written in base 10. %Y A265513 Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509. %K A265513 nonn,base %O A265513 0,3 %A A265513 _N. J. A. Sloane_, Dec 09 2015