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%I #9 Jan 13 2020 12:01:39
%S 0,1,2,0,4,4,0,4,8,0,10,10,0,13,13,0,16,16,0,10,20,0,13,23,0,16,26,0,
%T 28,28,0,28,28,0,28,28,0,28,28,0,40,40,0,40,40,0,28,28,0,40,40,0,52,
%U 52,0,28,56,0,28,56,0,28,56,0,28,56,0,40,68,0,40,68,0,28,56,0,40,68,0,52,80,0,82,82,0,82,82,0,82
%N a(n) = largest base-3 palindrome m <= n such that every base-3 digit of m is <= the corresponding digit of n; m is written in base 10.
%H Robert Israel, <a href="/A265511/b265511.txt">Table of n, a(n) for n = 0..10000</a>
%p F:= proc(n) local L;
%p L:= convert(n,base,3);
%p if L[1] = 0 then return 0 fi;
%p add(min(L[i],L[-i])*3^(i-1),i=1..nops(L))
%p end proc:
%p map(F, [$0..100]); # _Robert Israel_, Jan 13 2020
%Y Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509.
%K nonn,base,look
%O 0,3
%A _N. J. A. Sloane_, Dec 09 2015
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