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%I #6 Mar 30 2012 18:58:12
%S 1,2,3,4,6,8,9,12,13,15,16,17,18,19,21,24,25,26,27,30,32,33,34,35,36,
%T 38,39,42,43,45,47,48,49,50,51,52,54,60,64,65,66,67,68,70,72,73,76,78,
%U 84,86,90,91,94,96,97,98,99,100,102,104,105,108,117,120,121,128
%N (1/5)A206715.
%C It is conjectured that all the terms of this sequence are integers; this may be equivalent to the conjecture at A131853.
%t t = Table[IntegerDigits[n, 2], {n, 1, 3000}];
%t b[n_] := Reverse[Table[x^k, {k, 0, n}]]
%t p[n_, x_] := p[n, x] = t[[n]].b[-1 + Length[t[[n]]]]
%t TableForm[Table[{n, p[n, x], Factor[p[n, x]]},
%t {n, 1, 16}]]
%t u = {}; Do[n++; If[(p[n, x] /. x -> I) == 0,
%t AppendTo[u, n]], {n, 800}]
%t u (* A206715 *)
%t u/5 (* A206716 *)
%Y Cf. A131853, A206074, A206715.
%K nonn
%O 1,2
%A _Clark Kimberling_, Feb 11 2012