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A206073 Binary numbers that represent irreducible polynomials over the rationals with coefficients restricted to {0,1}. 14
10, 11, 101, 111, 1011, 1101, 10001, 10011, 10111, 11001, 11101, 11111, 100101, 101001, 101011, 101111, 110101, 110111, 111011, 111101, 1000011, 1000101, 1000111, 1001001, 1001101, 1001111, 1010001, 1010011, 1010111, 1011001 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The polynomial x^d(0) + x^d(1) + ... + d(n), where d(i) is 0 or 1 for 0<=i<=n and d(0)=1, matches the binary number d(0)d(1)...d(n).  (This is an enumeration of all the nonzero polynomials with coefficients in {0,1}, not just those that are irreducible.)

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

The matching of binary numbers to the first six polynomials irreducible over the field of rational numbers:

10 .... x

11 .... x + 1

101 ... x^2 + 1

111 ... x^2 + x + 1

1011 .. x^3 + x + 1

MATHEMATICA

t = Table[IntegerDigits[n, 2], {n, 1, 850}];

b[n_] := Reverse[Table[x^k, {k, 0, n}]]

p[n_, x_] := t[[n]].b[-1 + Length[t[[n]]]]

Table[p[n, x], {n, 1, 15}]

u = {}; Do[n++; If[IrreduciblePolynomialQ[p[n, x]],

AppendTo[u, n]], {n, 300}];

u                         (* A206074 *)

Complement[Range[200], u] (* A205783 *)

b[n_] := FromDigits[IntegerDigits[u, 2][[n]]]

Table[b[n], {n, 1, 40}]   (* A206073 *)

CROSSREFS

Cf. A171000 (irreducible Boolean polynomials).

Cf. A205783 (complement), A206074 (base 10).

Sequence in context: A157845 A230297 A086084 * A004676 A303593 A124387

Adjacent sequences:  A206070 A206071 A206072 * A206074 A206075 A206076

KEYWORD

nonn,base

AUTHOR

Clark Kimberling, Feb 03 2012

STATUS

approved

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Last modified September 21 08:38 EDT 2020. Contains 337268 sequences. (Running on oeis4.)