A125292 - OEIS

A125292

Numbers having either no ones or no twos in their ternary representation.

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

1,2

COMMENTS

Complement of A125293; union of A005823 and A005836;

A125291(a(n)) = 1; A062756(a(n))*A081603(a(n)) = 0.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..8190

Eric Weisstein's World of Mathematics, Ternary

Eric Weisstein's World of Mathematics, Repdigit

MATHEMATICA

not[n_]:=Module[{c=DigitCount[n, 3]}, c[[1]]==0||c[[2]]==0]; Select[ Range[ 250], not] (* Harvey P. Dale, Dec 15 2012 *)

PROG

(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

CROSSREFS

Subsequence of A154314.

Cf. A007089, A125289.

Sequence in context: A354148 A015858 A321473 * A101513 A153276 A298866

Adjacent sequences: A125289 A125290 A125291 * A125293 A125294 A125295

KEYWORD

nonn,base,easy

AUTHOR

Reinhard Zumkeller, Nov 26 2006

STATUS

approved