

A321802


Delete all consecutive identical decimal digits of n; write 1 if all digits disappear.


6



0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 1, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 1, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 1, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 1, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 1, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 1, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 1, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 1, 1, 101, 102, 103, 104, 105, 106, 107, 108, 109, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 120, 121, 1
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OFFSET

0,3


COMMENTS

Consecutive identical digits of n are erased. Leading zeros are erased unless the result is 0. If all digits are erased, we write 1 for the result (A321801 is another version, which uses 0 for the empty string).
More than the usual number of terms are shown in order to reach some interesting examples. Agrees with A320485 for n < 101.


LINKS

Chai Wah Wu, Table of n, a(n) for n = 0..10000


EXAMPLE

12311 becomes 123, 1123 becomes 23, 11231 becomes 231, and 110232 becomes 232 (as we don't accept leading zeros). Note that 112233 disappears immediately and we get 1.
1110 becomes 0 and 11000, 1100011 all become 1.


PROG

(Python)
from re import split
def A321802(n):
return (lambda x: int(x) if x != '' else 1)(''.join(d if len(d) == 1 else '' for d in split('(0+)(1+)(2+)(3+)(4+)(5+)(6+)(7+)(8+)(9+)', str(n)) if d != '' and d != None))
(PARI) apply( A321802(n)={if(n, forstep(i=#n=digits(n), 2, 1, n[i]!=n[i1]&&next; if(i<3n[i2]!=n[i], n=n[^i]; i); n=n[^i]); if(#n, fromdigits(n), 1))}, [0..122]) \\ M. F. Hasler, Nov 20 2018


CROSSREFS

Cf. A320485, A321801.
Sequence in context: A084905 A180409 A320485 * A337864 A106612 A137564
Adjacent sequences: A321799 A321800 A321801 * A321803 A321804 A321805


KEYWORD

sign,base


AUTHOR

Chai Wah Wu, Nov 19 2018


STATUS

approved



