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

%I A321803 #20 Dec 02 2018 15:06:51
%S A321803 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,
%T A321803 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,
%U A321803 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
%N A321803 Keep only consecutive identical decimal digits of n; write 0 if all digits disappear.
%C A321803 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).
%C A321803 More than the usual number of terms are shown in order to reach some interesting examples. Agrees with A321797 for n < 121.
%C A321803 Differs from A321538 for the first time at n = 11011. - _Chai Wah Wu_, Nov 29 2018
%e A321803 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.
%t A321803 Array[FromDigits[Join @@ Select[Split@ IntegerDigits@ #, Length@ # >= 2 &] /. {} -> {0}] &, 200, 0] (* _Michael De Vlieger_, Nov 20 2018 *)
%o A321803 (Python)
%o A321803 from re import split
%o A321803 def A321803(n):
%o A321803     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))
%Y A321803 Cf. A320486, A321800, A321797, A321538.
%K A321803 nonn,base
%O A321803 0,12
%A A321803 _Chai Wah Wu_, Nov 19 2018