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 A321801 Delete all consecutive identical decimal digits of n; write 0 if all digits disappear. 6
 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 0, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 0, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 0, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 0, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 0, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 0, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 0, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 0, 1, 101, 102, 103, 104, 105, 106, 107, 108, 109, 0, 0, 2, 3, 4, 5, 6, 7, 8, 9, 120, 121, 1, 123, 124, 125, 126, 127, 128, 129, 130, 131 (list; graph; refs; listen; history; text; internal format)
 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 0 for the result (A321802 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 A320486 for n < 101. LINKS 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 0. 1110, 11000, 1100011 all become 0. PROG (Python) from re import split def A321801(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)) (PARI) A321801(n)={forstep(i=#n=digits(n), 2, -1, n[i]!=n[i-1]&&next; if(i<3||n[i-2]!=n[i], n=n[^i]; i--); n=n[^i]); fromdigits(n)} \\ M. F. Hasler, Nov 20 2018 CROSSREFS Cf. A320486, A321802. Sequence in context: A329079 A306580 A320486 * A278946 A322629 A190599 Adjacent sequences:  A321798 A321799 A321800 * A321802 A321803 A321804 KEYWORD nonn,base AUTHOR Chai Wah Wu, Nov 19 2018 STATUS approved

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Last modified August 8 11:31 EDT 2020. Contains 336298 sequences. (Running on oeis4.)