

A115489


Number of monic irreducible polynomials of degree 3 in GF(2^n)[x].


1



2, 20, 168, 1360, 10912, 87360, 699008, 5592320, 44739072, 357913600, 2863310848, 22906490880, 183251935232, 1466015498240, 11728124018688, 93824992215040, 750599937851392, 6004799503073280, 48038396025110528
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OFFSET

1,1


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Max Alekseyev, Formula for the number of monic irreducible polynomials in a finite field
Max Alekseyev, PARI scripts for various problems
Index entries for linear recurrences with constant coefficients, signature (10,16).


FORMULA

a(0)=0, a(1)=2, a(n)=10a(n1)16a(n2).  T. D. Noe, Nov 30 2006
a(n) = (1/3)*2^n+(1/3)*8^n, with n>=0.  Paolo P. Lava, Jun 12 2008
G.f.: 2*x / ( (8*x1)*(2*x1) ).  R. J. Mathar, Jul 23 2014


MATHEMATICA

LinearRecurrence[{10, 16}, {2, 20}, 30] (* Harvey P. Dale, Sep 25 2013 *)
CoefficientList[Series[2/((8 x  1) (2 x  1)), {x, 0, 30}], x] (* Vincenzo Librandi, Jul 25 2014 *)


PROG

(MAGMA) [(1/3)*2^n+(1/3)*8^n: n in [1..20]]; // Vincenzo Librandi, Jul 25 2014


CROSSREFS

Cf. A115457A115505.
Sequence in context: A043029 A164944 A144485 * A105493 A067641 A279462
Adjacent sequences: A115486 A115487 A115488 * A115490 A115491 A115492


KEYWORD

nonn


AUTHOR

Max Alekseyev, Jan 16 2006


STATUS

approved



