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A265523 a(n) = largest base-9 palindrome m <= n such that every base-9 digit of m is <= the corresponding digit of n; m is written in base 10.

%I A265523 #12 Jan 13 2020 12:01:28
%S A265523 0,1,2,3,4,5,6,7,8,0,10,10,10,10,10,10,10,10,0,10,20,20,20,20,20,20,
%T A265523 20,0,10,20,30,30,30,30,30,30,0,10,20,30,40,40,40,40,40,0,10,20,30,40,
%U A265523 50,50,50,50,0,10,20,30,40,50,60,60,60,0,10,20,30,40,50,60,70,70,0,10,20,30,40,50,60,70,80,0,82,82
%N A265523 a(n) = largest base-9 palindrome m <= n such that every base-9 digit of m is <= the corresponding digit of n; m is written in base 10.
%H A265523 Robert Israel, <a href="/A265523/b265523.txt">Table of n, a(n) for n = 0..10000</a>
%p A265523 F:= proc(n) local L;
%p A265523   L:= convert(n,base,9);
%p A265523 if L[1] = 0 then return 0 fi;
%p A265523   add(min(L[i],L[-i])*9^(i-1),i=1..nops(L))
%p A265523 end proc:
%p A265523 map(F, [$0..100]); # _Robert Israel_, Jan 13 2020
%Y A265523 Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509.
%K A265523 nonn,base,look
%O A265523 0,3
%A A265523 _N. J. A. Sloane_, Dec 09 2015