The Hofstadter male-female sequences are the pair of sequences defined by ,,
and
(1)
(2)
for integers.
The first few terms of the "male" sequence for ,
1, ... are 0, 0, 1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, ... (OEIS A005379),
and of the "female" sequence are 1, 1, 2, 2, 3, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, ...
(OEIS A005378).
, 
,
and
.
The first few terms of the "male" sequence 
for 
,
1, ... are 0, 0, 1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 7, 8, 9, 9, ... (OEIS A005379),
and of the "female" sequence 
are 1, 1, 2, 2, 3, 3, 4, 5, 5, 6, 6, 7, 8, 8, 9, 9, ...
(OEIS A005378).
