A281499 Write n in binary reflected Gray code, interchange the 1's and 0's, reverse the code and convert it back to decimal.

1, 0, 0, 2, 4, 0, 2, 6, 12, 4, 0, 8, 10, 2, 6, 14, 28, 12, 4, 20, 16, 0, 8, 24, 26, 10, 2, 18, 22, 6, 14, 30, 60, 28, 12, 44, 36, 4, 20, 52, 48, 16, 0, 32, 40, 8, 24, 56, 58, 26, 10, 42, 34, 2, 18, 50, 54, 22, 6, 38, 46, 14, 30, 62, 124, 60, 28, 92, 76, 12, 44, 108, 100, 36, 4, 68, 84, 20, 52, 116, 112, 48, 16, 80, 64, 0, 32, 96, 104, 40, 8, 72, 88, 24, 56, 120

Offset: 0

Author

Indranil Ghosh, Jan 23 2017

Keywords

• nonn
• base

Examples

			For n = 11, the binary reflected Gray code for 11 is '1110' which after interchanging the 1's and 0's becomes '0001', which on reversing further gives '1000'. Now, 1000_2 = 8_10. So, a(11) = 8.
		

Links

• Indranil Ghosh, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A003188, A014550, A036044.

Programs

Mathematica

Table[FromDigits[Reverse@ IntegerDigits[#, 2] &@ BitXor[n, Floor[n/2]] /. { 0 -> 1, 1 -> 0}, 2], {n, 0, 120}] (* Michael De Vlieger, Jan 23 2017 *)

Python

def G(n):
    return bin(n^(n/2))[2:]
def a(n):
    s=""
    x=G(n)
    for i in x:
        if i=="1":s+="0"
        else:s+="1"
    s=s[::-1]
    return int(s,2)

Formula

a(n) = A036044(A003188(n)).