1,2
J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 55, p. 20, Ellipses, Paris 2008.
D. Wells, Curious and interesting numbers, Penguin Books, p. 108
Cf. A000045, A000217.
Sequence in context: A034186 A027499 A152773 * A033567 A181156 A162394
Adjacent sequences: A039592 A039593 A039594 * A039596 A039597 A039598
fini,nonn,full
Felice Russo (frusso(AT)micron.com)