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

3, 5, 7, 9, 10, 11, 13, 15, 17, 18, 19, 21, 22, 23, 25, 27, 29, 31, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 45, 46, 47, 49, 51, 53, 54, 55, 57, 59, 61, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89, 90, 91, 93, 94, 95, 97, 99, 101

Offset: 1

Author

Reinhard Zumkeller, Dec 17 2003

Keywords

• nonn
• base

Comments

A091064(a(n)) > 0, complement of A091065.

Includes all odd numbers > 1. - Robert Israel, Feb 05 2016

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to binary expansion of n

Crossrefs

Cf. A007088, A070939, A082461, A242869.

Programs

Maple

f:= proc(n) local L,m;
   if n::odd then return true fi;
   L:= convert(n,base,2);
   for m from 2 to nops(L)-1 do
     if L[1..m] = L[-m..-1] then return true fi;
   od:
   false
end proc:
select(f, [$2..101]); # Robert Israel, Feb 05 2016