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A337864 a(n) is the number formed by removing from n each digit if it is a duplicate of the previous digit, from left to right. 3
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 2, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 3, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 4, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 5, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 6, 67, 68, 69, 70, 71, 72, 73, 74 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
Please see discussion in A337857.
Similar to A137564 from which first differs at a(101) = 101 here, there a(101) = 10.
Differs from A106612 starting at n=100. - R. J. Mathar, Oct 08 2020
LINKS
EXAMPLE
a(100) = 10. Note that the second zero from the index n = 100 has been removed.
a(101) = 101.
a(1211323171) = 121323171. Note that the third "1" from the index n has been removed).
PROG
(Perl) sub a {my($n)=@_; $n =~ s/(.)\1+/$1/g; $n} # Kevin Ryde, Oct 04 2020
(Python)
from itertools import groupby
def a(n): return int("".join(k for k, g in groupby(str(n))))
print([a(n) for n in range(75)]) # Michael S. Branicky, Jul 23 2022
(PARI) a(n) = if(n < 10, return(n)); if(n%10 == (n\10)%10, return(a(n\10)), return(a(n\10)*10+n%10)) \\ David A. Corneth, Jul 23 2022
CROSSREFS
Cf. A043096 (fixed points a(n)=n).
Cf. A090079 (in binary).
Sequence in context: A180409 A320485 A321802 * A106612 A137564 A056960
KEYWORD
base,nonn
AUTHOR
Rodolfo Kurchan, Sep 27 2020
STATUS
approved

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Last modified July 13 15:08 EDT 2024. Contains 374284 sequences. (Running on oeis4.)