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A206716 (1/5)A206715. 2
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, 38, 39, 42, 43, 45, 47, 48, 49, 50, 51, 52, 54, 60, 64, 65, 66, 67, 68, 70, 72, 73, 76, 78, 84, 86, 90, 91, 94, 96, 97, 98, 99, 100, 102, 104, 105, 108, 117, 120, 121, 128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

It is conjectured that all the terms of this sequence are integers; this may be equivalent to the conjecture at A131853.

LINKS

Table of n, a(n) for n=1..66.

MATHEMATICA

t = Table[IntegerDigits[n, 2], {n, 1, 3000}];

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

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

TableForm[Table[{n, p[n, x], Factor[p[n, x]]},

  {n, 1, 16}]]

u = {}; Do[n++; If[(p[n, x] /. x -> I) == 0,

  AppendTo[u, n]], {n, 800}]

u    (* A206715 *)

u/5  (* A206716 *)

CROSSREFS

Cf. A131853, A206074, A206715.

Sequence in context: A265414 A189291 A155211 * A010385 A095037 A191284

Adjacent sequences:  A206713 A206714 A206715 * A206717 A206718 A206719

KEYWORD

nonn

AUTHOR

Clark Kimberling, Feb 11 2012

STATUS

approved

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Last modified December 5 05:39 EST 2021. Contains 349530 sequences. (Running on oeis4.)