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 A265516 #4 Dec 09 2015 20:23:08 %S A265516 0,1,2,3,4,0,11,11,11,11,0,11,22,22,22,0,11,22,33,33,0,11,22,33,44,0, %T A265516 101,101,101,101,0,111,111,111,111,0,121,121,121,121,0,131,131,131, %U A265516 131,0,141,141,141,141,0,101,202,202,202,0,111,212,212,212,0,121,222,222,222,0,131,232,232,232,0,141,242,242,242 %N A265516 a(n) = largest base-5 palindrome m <= n such that every base-5 digit of m is <= the corresponding digit of n; m is written in base 5. %Y A265516 Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509. %K A265516 nonn,base %O A265516 0,3 %A A265516 _N. J. A. Sloane_, Dec 09 2015