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A365987 Multiply each term by 3 and erase the rightmost digit of the result: this leaves the sequence unchanged. 2
1, 4, 14, 47, 157, 524, 1747, 5824, 19414, 64714, 215714, 719047, 2396824, 7989414, 26631380, 88771267, 295904224, 986347414, 3287824714, 10959415714, 36531385714, 121771285714, 405904285714, 1353014285714, 4510047619047, 15033492063490, 50111640211634 (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.
LINKS
FORMULA
a(n) = ceiling(a(n-1)/3*10), starting a(1) = 1. - Alois P. Heinz, Sep 24 2023
EXAMPLE
a(1) = 1 and 3*1 = 3; erasing the rightmost digit 3 leaves nothing;
a(2) = 4 and 3*4 = 12; erasing the rightmost digit 2 leaves 1;
a(3) = 14 and 3*14 = 42; erasing the rightmost digit 2 leaves 4;
a(4) = 47 and 3*47 = 141; erasing the rightmost digit 1 leaves 14;
a(5) = 157 and 3*157 = 471; erasing the rightmost digit 1 leaves 47; 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, ceil(a(n-1)/3*10)) end:
seq(a(n), n=1..30); # Alois P. Heinz, Sep 24 2023
MATHEMATICA
NestList[Ceiling[#/3*10] &, 1, 26] (* Michael De Vlieger, Sep 24 2023 *)
CROSSREFS
Sequence in context: A289780 A320404 A137284 * A228178 A000908 A121095
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 April 20 03:03 EDT 2024. Contains 371798 sequences. (Running on oeis4.)