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 A265532 #6 Dec 09 2015 21:41:14 %S A265532 0,1,2,3,3,11,11,11,11,11,22,22,22,22,22,33,33,101,101,101,101,111, %T A265532 111,111,111,121,121,121,121,131,131,131,131,131,202,202,202,202,212, %U A265532 212,212,212,222,222,222,222,232,232,232,232,232,303,303,303,303,313,313,313,313,323,323,323,323,333,333,1001,1001 %N A265532 Largest base-4 palindrome m <= n, written in base 4. %Y A265532 Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509. %K A265532 nonn,base %O A265532 0,3 %A A265532 _N. J. A. Sloane_, Dec 09 2015