A Slow Relative of Hofstadter's Q-Sequence
Nathan Fox
Department of Mathematics
Rutgers University
110 Frelinghuysen Rd.
Piscataway, NJ 08854
USA
Abstract:
Hofstadter's Q-sequence remains an enigma fifty years after its
introduction. Initially, the terms of the sequence increase
monotonically by 0 or 1 at a time. But the 12th term exceeds the
11th by two, and monotonicity fails shortly thereafter. In this
paper, we add a third term to Hofstadter's recurrence in the most
natural way. We show that this new recurrence, along with a suitable
initial condition that naturally generalizes Hofstadter's initial
condition, generates a sequence whose terms all increase monotonically
by 0 or 1 at a time. Furthermore, we give a complete description of the
resulting frequency sequence, which allows the nth term of our sequence
to be computed efficiently. We conclude by showing that our sequence
cannot be easily generalized.
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(Concerned with sequences
A004001
A005185
A046699
A057198
A063882
A087777
A278055.)
Received January 2 2017; revised version received June 26 2017.
Published in Journal of Integer Sequences, July 2 2017.
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