A365986 Multiply each term by 3 and erase the leftmost digit of the result: this leaves the sequence unchanged.

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

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