1,3

E. R. Berlekamp, Algebraic Coding Theory, McGraw-Hill, NY, 1968, p. 84.

T. L. Booth, An analytical representation of signals in sequential networks, pp. 301-3240 of Proceedings of the Symposium on Mathematical Theory of Automata. New York, N.Y., 1962. Microwave Research Institute Symposia Series, Vol. XII; Polytechnic Press of Polytechnic Inst. of Brooklyn, Brooklyn, N.Y. 1963 xix+640 pp. See p. 303.

R. Church, Tables of irreducible polynomials for the first four prime moduli, Annals Math., 36 (1935), 198-209.

P. Fan and M. Darnell, Sequence Design for Communications Applications, Wiley, NY, 1996, Table 5.1, p. 118.

W. W. Peterson and E. J. Weldon, Jr., Error-Correcting Codes. MIT Press, Cambridge, MA, 2nd edition, 1972, p. 476.

M. P. Ristenblatt, Pseudo-Random Binary Coded Waveforms, pp. 274-314 of R. S. Berkowitz, editor, Modern Radar, Wiley, NY, 1965; see p. 296.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

David W. Wilson, Table of n, a(n) for n=1..400

Joerg Arndt, Fxtbook

P. Koopman, Complete lists up to N=32

F. Ruskey, Primitive and Irreducible Polynomials

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

with(numtheory): phi(2^n-1)/n;

Table[EulerPhi[(2^n - 1)]/n, {n, 1, 50}]

(PARI) a(n)=eulerphi(2^n-1)/n - Hauke Worpel (thebigh(AT)outgun.com), Jun 10 2008

See A058947 for initial terms. Cf. A001037, A000020.

Cf. A027695.

Sequence in context: A034422 A140833 A071908 this_sequence A117855 A086442 A071407

Adjacent sequences: A011257 A011258 A011259 this_sequence A011261 A011262 A011263

nonn,easy,nice

N. J. A. Sloane (njas(AT)research.att.com).