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 A265520 #4 Dec 09 2015 20:24:32 %S A265520 0,1,2,3,4,5,6,0,11,11,11,11,11,11,0,11,22,22,22,22,22,0,11,22,33,33, %T A265520 33,33,0,11,22,33,44,44,44,0,11,22,33,44,55,55,0,11,22,33,44,55,66,0, %U A265520 101,101,101,101,101,101,0,111,111,111,111,111,111,0,121,121,121,121,121,121,0,131,131,131,131,131,131,0 %N A265520 a(n) = largest base-7 palindrome m <= n such that every base-7 digit of m is <= the corresponding digit of n; m is written in base 7. %Y A265520 Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509. %K A265520 nonn,base %O A265520 0,3 %A A265520 _N. J. A. Sloane_, Dec 09 2015