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 A365986 Multiply each term by 3 and erase the leftmost digit of the result: this leaves the sequence unchanged. 2
 1, 7, 9, 13, 71, 57, 119, 373, 791, 597, 1199, 3733, 7911, 12637, 70879, 90293, 63431, 54477, 118159, 706053, 1235351, 3745117, 7915039, 9305013, 13101671, 37700557, 79233519, 126411173, 375470391, 1125156797, 3708385599, 11236128533, 37078709511, 112359569837 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This is the lexicographically earliest sequence of distinct positive terms with this property. If the erasure of the leftmost digit leaves one or more leading zeros in the result, erase also those zeros. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..2000 EXAMPLE a(1) = 1 and 3*1 = 3; erasing the leftmost digit 3 leaves nothing; a(2) = 7 and 3*7 = 21; erasing the leftmost digit 2 leaves 1; a(3) = 9 and 3*9 = 27; erasing the leftmost digit 2 leaves 7; a(4) = 13 and 3*13 = 39; erasing the leftmost digit 3 leaves 9; a(5) = 71 and 3*71 = 213; erasing the leftmost digit 2 leaves 13; etc. We see that the last column of the above table is the sequence itself. MAPLE a:= proc(n) option remember; `if`(n=1, 1, (t-> parse(cat(3-irem(t, 3), t))/3)(a(n-1))) end: seq(a(n), n=1..35); # Alois P. Heinz, Sep 24 2023 CROSSREFS Cf. A365987, A317591. Sequence in context: A032487 A332103 A160777 * A063189 A004472 A145827 Adjacent sequences: A365983 A365984 A365985 * A365987 A365988 A365989 KEYWORD nonn,base,easy AUTHOR Eric Angelini, Sep 24 2023 EXTENSIONS More terms from Alois P. Heinz, Sep 24 2023 STATUS approved

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Last modified July 16 08:10 EDT 2024. Contains 374345 sequences. (Running on oeis4.)