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A100909
Concatenate number of occurrences in n of each decimal digit from 0 to 9 and drop leading zeros.
1
1000000000, 100000000, 10000000, 1000000, 100000, 10000, 1000, 100, 10, 1, 1100000000, 200000000, 110000000, 101000000, 100100000, 100010000, 100001000, 100000100, 100000010, 100000001, 1010000000, 110000000, 20000000, 11000000
OFFSET
0,1
COMMENTS
n = 0 is normally represented as the single digit 0, so a(0) = 1000000000. This representation system is inherently ambiguous by disregarding the order of n's digits but without modification will correctly identify those digits for all numbers up to 999999999 decimal; i.e., a(999999999) = 9; and for many beyond (e.g., a(121212121212121212) = a(111222111222222111) = ... = 990000000). However, for any n in which more than 9 of any single digit occur, additional ambiguity is introduced unless some type of grouping is also used (say, parentheses around or bars over a group of consecutive digits when written) so that, for example, (10) is known to represent 9999999999 rather than 8.
EXAMPLE
a(12) = 110000000 as 12 consists only of one 1 and one 2, hence the following are concatenated: 0 1 1 0 0 0 0 0 0 0 and dropping the leading 0 gives 110000000 (= a(21) also).
CROSSREFS
Cf. A100910 (each number of digit occurrences is a separate term).
Sequence in context: A136961 A307478 A375380 * A260519 A260520 A033423
KEYWORD
base,easy,nonn
AUTHOR
Rick L. Shepherd, Nov 21 2004
STATUS
approved