[go: up one dir, main page]

login
A001115
Maximal number of pairwise relatively prime polynomials of degree n over GF(2).
(Formerly M0575 N0209)
1
1, 2, 3, 4, 6, 9, 14, 23, 38, 64, 113, 200, 358, 653, 1202, 2223, 4151, 7781, 14659, 27721, 52603, 100084, 190969, 365134, 699617, 1342923, 2582172, 4972385, 9588933, 18515328, 35794987, 69278386, 134224480, 260309786, 505302925, 981723316, 1908898002, 3714597352, 7233673969, 14096361346, 27487875487
OFFSET
0,2
COMMENTS
For n>=4, a maximal set can be chosen by taking all irreducible polynomials of degree n, the squares of all irreducible polynomials of degree n/2 (if n is even) and, for each irreducible polynomial p of degree d with 1 <= d < n/2, a product p*q where q is irreducible of degree n-d. The q's should all be distinct, which is possible when n>=4.
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
D. C. Bossen and S. S. Yau, Redundant residue polynomial codes, Information and Control 13 (1968) 597-618.
FORMULA
a(n) = P(n) + Sum_{i=1..floor(n/2)} P(i), where P(n) = A001037(n) = number of irreducible polynomials of degree n.
EXAMPLE
n=1: x and x+1.
n=2: x^2, x^2+1, x^2+x+1.
n=3: x^3, x^3+1, x^3+x+1, x^3+x^2+1.
MATHEMATICA
p[0]=1; p[n_] := Sum[If[Mod[n, d]==0, MoebiusMu[n/d]2^d, 0], {d, 1, n}]/n; a[n_] := p[n]+Sum[p[i], {i, 1, Floor[n/2]}]
PROG
(PARI) A001115(n)=A001037(n)+sum(i=1, n\2, A001037(i)) \\ M. F. Hasler, Jan 11 2016
CROSSREFS
Cf. A001037.
Sequence in context: A005579 A000381 A350588 * A173278 A173289 A096824
KEYWORD
nonn
EXTENSIONS
Edited by Dean Hickerson, Nov 18 2002
More terms from M. F. Hasler, Jan 11 2016
STATUS
approved