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A216842 Degree of the smallest irreducible polynomial factor for the polynomial (x^(2n+1)+1)/(x+1) over GF(2). 0
0, 2, 4, 3, 2, 10, 12, 2, 8, 18, 2, 11, 4, 2, 28, 5, 2, 3, 36, 2, 20, 14, 2, 23, 3, 2, 52, 4, 2, 58, 60, 2, 4, 66, 2, 35, 9, 2, 3, 39, 2, 82, 4, 2, 11, 3, 2, 4, 48, 2, 100, 51, 2, 106, 36, 2, 28, 4, 2, 3, 10, 2, 4, 7, 2, 130, 3, 2, 68, 138, 2, 10, 4, 2, 148 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..74.

MATHEMATICA

Join[{0}, Table[Exponent[FactorList[Sum[x^i, {i, 0, 2*n}], Modulus -> 2][[2, 1]], x], {n, 100}]] (* T. D. Noe, Sep 19 2012 *)

PROG

(PARI) vector(100, p, factormod((x^(2*p+1)+1)/(x+1), 2, 1)[1, 1])

CROSSREFS

Cf. A002326, A001122.

Sequence in context: A269599 A059908 A084936 * A099066 A021415 A244646

Adjacent sequences:  A216839 A216840 A216841 * A216843 A216844 A216845

KEYWORD

nonn

AUTHOR

V. Raman, Sep 17 2012

STATUS

approved

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Last modified February 21 15:34 EST 2019. Contains 320374 sequences. (Running on oeis4.)