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A265526 Largest base-2 palindrome m <= n, written in base 2. 1
0, 1, 1, 11, 11, 101, 101, 111, 111, 1001, 1001, 1001, 1001, 1001, 1001, 1111, 1111, 10001, 10001, 10001, 10001, 10101, 10101, 10101, 10101, 10101, 10101, 11011, 11011, 11011, 11011, 11111, 11111, 100001, 100001, 100001, 100001, 100001, 100001, 100001, 100001, 100001, 100001, 100001, 100001, 101101, 101101, 101101 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
LINKS
MAPLE
ispal:= proc(n) global b; # test for base-b palindrome
local L, Ln, i;
L:= convert(n, base, b);
Ln:= nops(L);
for i from 1 to floor(Ln/2) do
if L[i] <> L[Ln+1-i] then return(false); fi;
od:
return(true);
end proc;
# find max pal <= n, write in base 10
less10:=proc(n) global b;
local t1, t2, i, m, sw1, L2;
t1:=convert(n, base, b);
for m from n by -1 to 0 do
if ispal(m) then return(m); fi;
od;
end proc;
# find max pal <= n, write in base b
lessb:=proc(n) global b;
local t1, t2, i, m, mb, sw1, L2;
t1:=convert(n, base, b);
for m from n by -1 to 0 do
if ispal(m) then
t2:=convert(m, base, b);
L2:=nops(t2);
mb:=add(t2[i]*10^(i-1), i=1..L2); return(mb); fi;
od;
end proc;
b:=2;
[seq(less10(n), n=0..100)]; # A206913
[seq(lessb(n), n=0..100)]; # A265526
[seq(less10(2*n), n=0..100)]; # A265527
[seq(lessb(2*n), n=0..100)]; # A265528
b:=10;
[seq(less10(n), n=0..100)]; # A261423
CROSSREFS
Sequences related to palindromic floor and ceiling: A175298, A206913, A206914, A261423, A262038, and the large block of consecutive sequences beginning at A265509.
Sequence in context: A243127 A088761 A215256 * A265559 A265543 A062128
KEYWORD
nonn,base
AUTHOR
N. J. A. Sloane, Dec 09 2015
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)