cp's OEIS Frontend

A091066 Numbers having in binary representation at least one proper prefix that is also a suffix.

%I A091066 #20 Feb 05 2016 02:50:07
%S A091066 3,5,7,9,10,11,13,15,17,18,19,21,22,23,25,27,29,31,33,34,35,36,37,38,
%T A091066 39,41,42,43,45,46,47,49,51,53,54,55,57,59,61,63,65,66,67,68,69,70,71,
%U A091066 73,74,75,76,77,78,79,81,82,83,85,86,87,89,90,91,93,94,95,97,99,101
%N A091066 Numbers having in binary representation at least one proper prefix that is also a suffix.
%C A091066 A091064(a(n)) > 0, complement of A091065.
%C A091066 Includes all odd numbers > 1. - _Robert Israel_, Feb 05 2016
%H A091066 Alois P. Heinz, <a href="/A091066/b091066.txt">Table of n, a(n) for n = 1..10000</a>
%H A091066 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%p A091066 f:= proc(n) local L,m;
%p A091066    if n::odd then return true fi;
%p A091066    L:= convert(n,base,2);
%p A091066    for m from 2 to nops(L)-1 do
%p A091066      if L[1..m] = L[-m..-1] then return true fi;
%p A091066    od:
%p A091066    false
%p A091066 end proc:
%p A091066 select(f, [$2..101]); # _Robert Israel_, Feb 05 2016
%Y A091066 Cf. A007088, A070939, A082461, A242869.
%K A091066 nonn,base
%O A091066 1,1
%A A091066 _Reinhard Zumkeller_, Dec 17 2003