The value of the 20 bit in a binary number. For the sequence of numbers 1, 2, 3, 4, ..., the least significant bits are therefore the alternating sequence 1, 0, 1, 0, 1, 0, ... (Sloane's A000035). It can be represented as
 |
 |
 |
(1) |
|
 |
(2) |
or
 |
(3) |
If also is given by the linear recurrence equation
 |
(4) |
with 
(Wolfram 2002, p. 128).
Similarly, the "most significant bit" is the value of the 
bit in an n-bit representation.
Sloane, N. J. A. Sequences A000035/M0001 in "The On-Line Encyclopedia of Integer Sequences." http://www.research.att.com/~njas/sequences/.
Whitford, A. K. "Binet's Formula Generalized." Fib. Quart. 15, 21, 24, and 29, 1977.
Wolfram, S. A New Kind of Science. Champaign, IL: Wolfram Media, p. 128, 2002.