A131203 Number of cycles of length n under the mapping x -> x^2-2 modulo Fermat prime 2^(2^m)+1, where m is any fixed integer such that n divides 2^m-1.

1, 1, 3, 9, 28, 93, 315, 1091, 3855, 13797, 49929, 182361, 671088, 2485504, 9256395, 34636833, 130150493, 490853403, 1857283155, 7048151355, 26817356775, 102280151421, 390937467284, 1497207322929, 5744387279808, 22076468760335

Offset

0,3

Comments

Halved bisection of A001037.

Bisection of A000048. Number of 2m bead balanced binary necklaces of fundamental period 4n+2 that are equivalent to their complements, where m is any multiple of 2n+1. - Aaron Meyerowitz, Jun 01 2024

Links

Table of n, a(n) for n=0..25.

Formula

a(n) = A001037(2n+1)/2.

Crossrefs

Cf. A000048, A001037, A059966.

Sequence in context: A243156 A228449 A368288 * A191637 A345241 A238978

Adjacent sequences: A131200 A131201 A131202 * A131204 A131205 A131206

Keyword

nonn

Author

Max Alekseyev, Sep 27 2007

Status

approved