G. H. Hardy & E. M. Wright (1979):
An introduction to the theory of numbers.
The Clarendon Press, Oxford University Press,
New York.
Kenneth R. Rebman (1975):
The sequence: 1 5 16 45 121 320in combinatorics.
Fibonacci Quart. 13,
pp. 51–55.
Beno^ıt Rittaud & Laurent Vivier:
Circular words and three applications: factors of the Fibonacci word, F-adic numbers, and the sequence 1, 5, 16, 45, 121, 320,.
To appear in Functiones et Approximatio Commentarii Mathematici.