Hofstadter Male-Female Sequences

The pair of sequences defined by $F(0)=1$, $M(0)=0$, and

$$F(n) = n-M(F(n-1))$$

$$M(n) = n-F(M(n-1)).$$

The first few terms of the ``male'' sequence $M(n)$ are 0, 1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, ... (Sloane's A005379), and the first few terms of the ``female'' sequence $F(n)$ are 1, 2, 2, 3, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, ... (Sloane's A005378).

References

Hofstadter, D. R. Gödel, Escher, Bach: An Eternal Golden Braid. New York: Vintage Books, p. 137, 1989.

Sloane, N. J. A. Sequences A005378/M0263 and A005379/M0278 in ``An On-Line Version of the Encyclopedia of Integer Sequences.'' http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S. The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.