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A125292
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Numbers having either no ones or no twos in their ternary representation.
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7
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1, 2, 3, 4, 6, 8, 9, 10, 12, 13, 18, 20, 24, 26, 27, 28, 30, 31, 36, 37, 39, 40, 54, 56, 60, 62, 72, 74, 78, 80, 81, 82, 84, 85, 90, 91, 93, 94, 108, 109, 111, 112, 117, 118, 120, 121, 162, 164, 168, 170, 180, 182, 186, 188, 216, 218, 222, 224, 234, 236, 240, 242, 243
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OFFSET
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1,2
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COMMENTS
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LINKS
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Eric Weisstein's World of Mathematics, Ternary
Eric Weisstein's World of Mathematics, Repdigit
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MATHEMATICA
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not[n_]:=Module[{c=DigitCount[n, 3]}, c[[1]]==0||c[[2]]==0]; Select[ Range[ 250], not] (* Harvey P. Dale, Dec 15 2012 *)
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PROG
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(PARI) is(n, base=3) = #Set(select(sign, digits(n, base)))==1 \\ Rémy Sigrist, Mar 28 2020
(PARI) a(n, base=3) = { for (w=0, oo, if (n<=(base-1)*2^w, my (d=1+(n-1)\2^w, k=2^w+(n-1)%(2^w)); return (d*fromdigits(binary(k), base)), n -= (base-1)*2^w)) } \\ Rémy Sigrist, Mar 28 2020
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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