A321804 -id:A321804 - cp's OEIS frontend

A321803 Keep only consecutive identical decimal digits of n; write 0 if all digits disappear.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 22, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 33, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 44, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 55, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 66, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 77, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 88, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 99, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 111, 11, 11, 11, 11, 11, 11, 11, 11, 0, 0, 22, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 33, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 44, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 55, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 66, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 77, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 88, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 99

Offset: 0

Chai Wah Wu, Nov 19 2018

Consecutive identical digits of n are kept. Leading zeros are erased unless the result is 0. If all digits are erased, we write 0 for the result (A321804 is another version, which uses -1 for the empty string).
More than the usual number of terms are shown in order to reach some interesting examples. Agrees with A321797 for n < 121.
Differs from A321538 for the first time at n = 11011. - Chai Wah Wu, Nov 29 2018

			123321 becomes 33, 1123 becomes 11, 112331 becomes 1133, and 100223 becomes 22 (as we don't accept leading zeros). Note that 12321 disappears immediately and we get 0.

Cf. A320486, A321800, A321797, A321538.

Array[FromDigits[Join @@ Select[Split@ IntegerDigits@ #, Length@ # >= 2 &] /. {} -> {0}] &, 200, 0] (* Michael De Vlieger, Nov 20 2018 *)

from re import split
def A321803(n):
    return int('0'+''.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))

cp's OEIS Frontend

A321803 Keep only consecutive identical decimal digits of n; write 0 if all digits disappear.

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