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A173821
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The digital sum of a(n) is visible in the smallest a(n+1) not yet present in the sequence.
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4
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1, 10, 11, 2, 12, 3, 13, 4, 14, 5, 15, 6, 16, 7, 17, 8, 18, 9, 19, 100, 21, 23, 25, 27, 29, 110, 20, 22, 24, 26, 28, 101, 32, 35, 38, 111, 30, 31, 34, 37, 102, 33, 36, 39, 112, 40, 41, 45, 49, 113, 50, 51, 46, 103, 42, 56, 114, 60, 61, 47, 115, 57, 120, 43, 67, 130, 44, 48, 121
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OFFSET
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1,2
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COMMENTS
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a(1) = 1, and for n > 1 a(n) is the smallest integer not yet present in the sequence such that the digital sum of a(n-1) is a substring of the decimal digits of a(n).
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LINKS
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EXAMPLE
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The digital sum of 1 is 1, so a(2) is the first unused number containing a "1", 10 (1 is already used). The digital sum of 10 is 1, so a(3) is the first unused number containing a "1", 11 (1 and 10 are already used)... The digital sum of 19 is 10, so a(20) is the first unused number containing a "10", 100 (10 is already used).
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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