cp's OEIS Frontend

A265511 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.

%I A265511 #9 Jan 13 2020 12:01:39
%S A265511 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 A265511 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 A265511 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 A265511 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 A265511 Robert Israel, <a href="/A265511/b265511.txt">Table of n, a(n) for n = 0..10000</a>
%p A265511 F:= proc(n) local L;
%p A265511   L:= convert(n,base,3);
%p A265511   if L[1] = 0 then return 0 fi;
%p A265511   add(min(L[i],L[-i])*3^(i-1),i=1..nops(L))
%p A265511 end proc:
%p A265511 map(F, [$0..100]); # _Robert Israel_, Jan 13 2020
%Y A265511 Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509.
%K A265511 nonn,base,look
%O A265511 0,3
%A A265511 _N. J. A. Sloane_, Dec 09 2015