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A265526
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Largest base-2 palindrome m <= n, written in base 2.
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1
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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
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OFFSET
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0,4
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LINKS
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MAPLE
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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
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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