%N a(n) = the smallest integer m such that n = (the largest integer that, when represented in binary, occurs at least twice as a substring in the binary representation of m).
%C The substrings (each equal to the binary representation of n) may overlap in the binary representation of a(n). a(n) = the smallest positive integer such that A147755(a(n)) = n.
%H Alois P. Heinz, <a href="/A147756/b147756.txt">Table of n, a(n) for n = 0..8191</a>
%e 21 in binary is 10101. 101 (5 in decimal) occurs twice in 10101: (101)01 and 10(101). Since no larger integer (when represented in binary) occurs more than once within 10101 and since no smaller integer (represented in binary) contains the substring 101 within it at least twice, then a(5) = 21.
%Y Cf. A147755.
%A _Leroy Quet_, Nov 11 2008
%E Extended by _Ray Chandler_, Nov 14 2008