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A321800 Delete the decimal digits of n that appear exactly once; write -1 if all digits disappear. 4
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 22, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 33, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 44, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 55, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 66, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 77, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 88, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 99, 0, 11, -1, -1, -1, -1, -1, -1, -1, -1, 11, 111, 11, 11, 11, 11, 11, 11, 11, 11, -1, 11, 22, -1, -1, -1, -1, -1, -1, -1, -1, 11, -1, 33, -1, -1, -1, -1, -1, -1, -1, 11, -1, -1, 44, -1, -1, -1, -1, -1, -1, 11, -1, -1, -1, 55, -1, -1, -1, -1, -1, 11, -1, -1, -1, -1, 66, -1, -1, -1, -1, 11, -1, -1, -1, -1, -1, 77, -1, -1, -1, 11, -1, -1, -1, -1, -1, -1, 88, -1, -1, 11, -1, -1, -1, -1, -1, -1, -1, 99 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,12

COMMENTS

A companion sequence to A320485.

Digits that appear exactly once in n are erased. Leading zeros are erased unless the result is 0. If all digits are erased, we write -1 for the result (A321797 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.

LINKS

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

EXAMPLE

12321 becomes 1221, 1123 becomes 11, 11231 becomes 111, and 100223 becomes 22 (as we don't accept leading zeros). Note that 12345 disappears immediately and we get -1.

PROG

(Python)

def A321800(n):

    return (lambda x: int(x) if x != '' else -1)(''.join(d if str(n).count(d) != 1 else '' for d in str(n)))

CROSSREFS

Cf. A320485, A321797.

Sequence in context: A109014 A268357 A321804 * A130837 A010194 A280443

Adjacent sequences:  A321797 A321798 A321799 * A321801 A321802 A321803

KEYWORD

sign,base,look

AUTHOR

Chai Wah Wu, Nov 19 2018

STATUS

approved

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Last modified September 27 03:21 EDT 2020. Contains 337380 sequences. (Running on oeis4.)