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A051815
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Number of n-digit numbers with nonzero multiplicative digital root 4.
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1
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1, 12, 105, 780, 5452, 39979, 336081, 3263355, 34518027, 372779338, 3957184040, 40729856248, 406862880846, 3979167973684, 38556471560342, 374259579575061
(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)=4 }
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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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