Print numbers having first and last bits as the only set bits

Given a positive integer n. The problem is to print numbers in the range 1 to n having first and last bits as the only set bits.
Examples: 
 

Input : n = 10
Output : 1 3 5 9
(1)10 = (1)2.
(3)10 = (11)2.
(5)10 = (101)2.
(9)10 = (1001)2

 

Naive Approach: Print "1". Now for i = 3 to n, check if (i-1) is a Perfect power of two or not. If true then print i.
 

Output: 
 

1 3 5 9

Time Complexity : O(n)

Auxiliary Space: O(1)

Efficient Approach: Print "1". Now one by one generate perfect power of two (except '1') with the help of bitwise left shift operation. Bitwise xor these numbers with 1 and if result is in the range print them else stop.
 

Output: 

1 3 5 9

Time Complexity : O(logn)

Auxiliary Space: O(1)