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A014580 Binary irreducible polynomials (primes in the ring GF(2)[X]), evaluated at X=2. 95
2, 3, 7, 11, 13, 19, 25, 31, 37, 41, 47, 55, 59, 61, 67, 73, 87, 91, 97, 103, 109, 115, 117, 131, 137, 143, 145, 157, 167, 171, 185, 191, 193, 203, 211, 213, 229, 239, 241, 247, 253, 283, 285, 299, 301, 313, 319, 333, 351, 355, 357, 361, 369, 375 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Or, binary irreducible polynomials, interpreted as binary vectors, then written in base 10.

The numbers {a(n)} are a subset of the set {A206074}. - Thomas Ordowski, Feb 21 2014

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1377 (through degree 13)

Index entries for sequences operating on GF(2)[X]-polynomials

EXAMPLE

x^4 + x^3 + 1 -> 16+8+1 = 25. Or, x^4 + x^3 + 1 -> 11001 (binary) = 25 (decimal).

MATHEMATICA

fQ[n_] := Block[{ply = Plus @@ (Reverse@ IntegerDigits[n, 2] x^Range[0, Floor@ Log2@ n])}, ply == Factor[ply, Modulus -> 2] && n != 2^Floor@ Log2@ n]; fQ[2] = True; Select[ Range@ 378, fQ] (* Robert G. Wilson v, Aug 12 2011 *)

Reap[Do[If[IrreduciblePolynomialQ[IntegerDigits[n, 2] . x^Reverse[Range[0, Floor[Log[2, n]]]], Modulus -> 2], Sow[n]], {n, 2, 1000}]][[2, 1]] (* Jean-Fran├žois Alcover, Nov 21 2016 *)

PROG

(PARI) is(n)=polisirreducible(Pol(binary(n))*Mod(1, 2)) \\ Charles R Greathouse IV, Mar 22 2013

CROSSREFS

Cf. A000031, A001037, A048720. Written in binary: A058943.

Characteristic function: A091225. Inverse: A091227. a(n) = A091202(A000040(n)). Almost complement of A091242. Union of A091206 & A091214 and also of A091250 & A091252. First differences: A091223. Apart from a(1) and a(2), a subsequence of A092246 and hence A000069.

Sequence in context: A145673 A040116 A155153 * A197227 A091206 A038963

Adjacent sequences:  A014577 A014578 A014579 * A014581 A014582 A014583

KEYWORD

nonn

AUTHOR

David Petry (petry(AT)accessone.com)

STATUS

approved

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Last modified September 24 22:27 EDT 2018. Contains 315360 sequences. (Running on oeis4.)