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Numbers that match non-irreducible polynomials over {0,1,2}; complement of A207966.
3

%I #5 Mar 30 2012 18:58:13

%S 1,2,9,12,15,16,18,21,24,27,28,30,32,33,36,39,40,42,44,45,48,50,51,52,

%T 54,56,57,60,63,64,66,68,69,70,72,75,76,78,80,81,84,87,88,90,91,93,96,

%U 99,100,102,104,105,108,111,112,114,116,117,119,120,123,124

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

%C See A207966.

%e (See A207966.)

%t t = Table[IntegerDigits[n, 3], {n, 1, 850}];

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

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

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

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

%t AppendTo[u, n]], {n, 300}]; u (* A207966 *)

%t Complement[Range[200], u] (* A207967 *)

%t b[n_] := FromDigits[IntegerDigits[u, 3][[n]]]

%t Table[b[n], {n, 1, 50}] (* A207968 *)

%Y Cf. A207966, A207968.

%K nonn

%O 1,2

%A _Clark Kimberling_, Feb 21 2012