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A207670 Numbers that match polynomomials with coefficients in {0,1,2} that are not irreducible modulo 3; complement of A207670. 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See the Comments at A207669.

LINKS

Table of n, a(n) for n=1..67.

EXAMPLE

(See the Example section of A207669.)

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 *)

CROSSREFS

Cf. A207669.

Sequence in context: A300129 A191401 A085069 * A176545 A072065 A137000

Adjacent sequences:  A207667 A207668 A207669 * A207671 A207672 A207673

KEYWORD

nonn

AUTHOR

Clark Kimberling, Feb 26 2012

STATUS

approved

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Last modified August 24 23:01 EDT 2019. Contains 326314 sequences. (Running on oeis4.)