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 A208665 Numbers that match odd ternary polynomials; see Comments. 1
 3, 6, 27, 30, 33, 54, 57, 60, 243, 246, 249, 270, 273, 276, 297, 300, 303, 486, 489, 492, 513, 516, 519, 540, 543, 546, 2187, 2190, 2193, 2214, 2217, 2220, 2241, 2244, 2247, 2430, 2433, 2436, 2457, 2460, 2463, 2484, 2487, 2490, 2673, 2676, 2679 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The ternary polynomials (having all coefficients in {0,1,2}) are enumerated at A207966.  A208665 shows the numbers n for which p(n,-x)=-p(n,x). LINKS MATHEMATICA t = Table[IntegerDigits[n, 3], {n, 1, 4000}]; 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, 30}] even = {}; Do[n++; If[(p[n, x] /. x -> -x) == p[n, x], AppendTo[even, n]], {n, 1600}]; even     (* A037314 for n >= 2 *) odd = {}; Do[n++; If[(p[n, x] /. x -> -x) == -p[n, x], AppendTo[odd, n]], {n, 3900}]; odd      (* A208665 *) CROSSREFS Cf. A037314, A207966. Sequence in context: A304051 A128437 A200654 * A256762 A064283 A266857 Adjacent sequences:  A208662 A208663 A208664 * A208666 A208667 A208668 KEYWORD nonn AUTHOR Clark Kimberling, Feb 29 2012 STATUS approved

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Last modified March 18 16:00 EDT 2019. Contains 321292 sequences. (Running on oeis4.)