A207967 Numbers that match non-irreducible polynomials over {0,1,2}; complement of A207966.

1, 2, 9, 12, 15, 16, 18, 21, 24, 27, 28, 30, 32, 33, 36, 39, 40, 42, 44, 45, 48, 50, 51, 52, 54, 56, 57, 60, 63, 64, 66, 68, 69, 70, 72, 75, 76, 78, 80, 81, 84, 87, 88, 90, 91, 93, 96, 99, 100, 102, 104, 105, 108, 111, 112, 114, 116, 117, 119, 120, 123, 124

Offset

1,2

Comments

See A207966.

Links

Table of n, a(n) for n=1..62.

Example

(See A207966.)

Mathematica

t = Table[IntegerDigits[n, 3], {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  (* A207966 *)
Complement[Range[200], u]        (* A207967 *)
b[n_] := FromDigits[IntegerDigits[u, 3][[n]]]
Table[b[n], {n, 1, 50}]          (* A207968 *)

Crossrefs

Cf. A207966, A207968.

Sequence in context: A030376 A080520 A032372 * A265413 A297830 A103008

Adjacent sequences: A207964 A207965 A207966 * A207968 A207969 A207970

Keyword

nonn

Author

Clark Kimberling, Feb 21 2012

Status

approved