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A051818
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Number of n-digit numbers with nonzero multiplicative digital root 7.
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1
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1, 3, 14, 86, 666, 6418, 64079, 597445, 5116146, 40671872, 304752986, 2187716324, 15395364971, 110611591118, 866239098731, 7907500662596
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,2
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REFERENCES
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William Mayne, sci.math, Jun 15 1991
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LINKS
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FORMULA
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# { i : 10^(n-1) < i < 10^n and A051802(i)=7 }
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CROSSREFS
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KEYWORD
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nonn,base,hard
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AUTHOR
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STATUS
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approved
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