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A223077 Positive integers, written in base 3, with the property that if the base-3 representation is reversed the result is twice the original number. 3
1012, 10212, 102212, 1022212, 10121012, 10222212, 101201012, 102222212, 1012001012, 1021210212, 1022222212, 10120001012, 10212010212, 10222222212, 101200001012, 101210121012, 102120010212, 102212102212, 102222222212, 1012000001012, 1012102121012, 1021200010212, 1022120102212, 1022222222212 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the decimal representations of these same numbers see A173951.

Theorem: The number of terms of length n is equal to A103609(n-2).

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..108

MATHEMATICA

b3rQ[n_]:=FromDigits[Reverse[IntegerDigits[n]], 3]/FromDigits[ IntegerDigits[ n], 3] ==2; Select[FromDigits/@Tuples[{0, 1, 2}, 13], b3rQ]//Quiet (* Harvey P. Dale, Jun 10 2018 *)

CROSSREFS

Cf. A173951, A214927.

Sequence in context: A072140 A080467 A023058 * A206191 A249987 A224920

Adjacent sequences:  A223074 A223075 A223076 * A223078 A223079 A223080

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Mar 14 2013

STATUS

approved

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Last modified November 12 14:43 EST 2019. Contains 329058 sequences. (Running on oeis4.)