A207670 Numbers that match polynomials with coefficients in {0,1,2} that are not irreducible modulo 3; complement of A207670.

1, 2, 9, 11, 12, 13, 15, 16, 18, 19, 21, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33, 36, 37, 39, 40, 42, 44, 45, 47, 48, 50, 51, 52, 54, 55, 56, 57, 60, 61, 62, 63, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 81, 82, 83, 84, 85, 87, 88, 90, 91, 93, 95, 96, 98, 99, 100

Offset: 1

Author

Clark Kimberling, Feb 26 2012

Keywords

• nonn

Comments

See the Comments at A207669.

Examples

			(See the Example section of A207669.)
		

Crossrefs

Cf. A207669.

Programs

Mathematica

t = Table[IntegerDigits[n, 3], {n, 1, 1000}];
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], Modulus -> 3],
  AppendTo[u, n]], {n, 1, 400}]
u                           (* A207669 *)
Complement[Range[200], %]   (* A207670 *)
b[n_] := FromDigits[IntegerDigits[u, 3][[n]]]
Table[b[n], {n, 1, 50}]     (* A207671 *)