OFFSET
1,1
COMMENTS
The initial 2 should really be a 1. See A011260 for official version.
REFERENCES
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.
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.
LINKS
David W. Wilson, Table of n, a(n) for n = 1..400
R. Church, Tables of irreducible polynomials for the first four prime moduli, Annals Math., 36 (1935), 198-209.
S. V, Duzhin and D. V. Pasechnik, Groups acting on necklaces and sandpile groups, 2014. See p. 92. - N. J. A. Sloane, Jun 30 2014
MATHEMATICA
Table[If[n==1, 2, EulerPhi[2^n-1]/n], {n, 1, 50}] (* Vladimir Joseph Stephan Orlovsky, Jan 24 2012 *)
PROG
(PARI) a(n)=if(n==1, 2, eulerphi(2^n-1)/n) \\ Hauke Worpel (thebigh(AT)outgun.com), Jun 10 2008
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved