cp's OEIS Frontend

A206285 Numbers that match polynomials not irreducible over the nonnegative integers.

%I A206285 #8 Mar 30 2012 18:58:12
%S A206285 1,2,4,5,7,8,11,13,14,15,16,17,19,21,23,25,26,29,31,32,33,34,35,37,38,
%T A206285 39,41,43,45,47,49,51,53,55,57,58,59,61,62,63,64,65,67,69,71,73,74,75,
%U A206285 77,78,79,82,83,84,85,86,87,89,90,91,93,94,95,97,99,101,103
%N A206285 Numbers that match polynomials not irreducible over the nonnegative integers.
%C A206285 Complement of A206284.
%e A206285 (See the example at A206284.)
%t A206285 b[n_] := Table[x^k, {k, 0, n}];
%t A206285 f[n_] := f[n] = FactorInteger[n]; z = 400;
%t A206285 t[n_, m_, k_] := If[PrimeQ[f[n][[m, 1]]] && f[n][[m, 1]]
%t A206285 == Prime[k], f[n][[m, 2]], 0];
%t A206285 u = Table[Apply[Plus,
%t A206285     Table[Table[t[n, m, k], {k, 1, PrimePi[n]}], {m, 1,
%t A206285       Length[f[n]]}]], {n, 1, z}];
%t A206285 p[n_, x_] := u[[n]].b[-1 + Length[u[[n]]]]
%t A206285 Table[p[n, x], {n, 1, z/4}]
%t A206285 v = {}; Do[n++; If[IrreduciblePolynomialQ[p[n, x]],
%t A206285 AppendTo[v, n]], {n, z/2}]; v  (* A206284 *)
%t A206285 Complement[Range[200], v]      (* A206285 *)
%Y A206285 Cf. A206285, A206331.
%K A206285 nonn
%O A206285 1,2
%A A206285 _Clark Kimberling_, Feb 05 2012