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A051818 Number of n-digit numbers with nonzero multiplicative digital root 7. 1
1, 3, 14, 86, 666, 6418, 64079, 597445, 5116146, 40671872, 304752986, 2187716324, 15395364971, 110611591118, 866239098731, 7907500662596 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

William Mayne, sci.math, Jun 15 1991

LINKS

Table of n, a(n) for n=1..16.

FORMULA

# { i : 10^(n-1) < i < 10^n and A051802(i)=7 }

CROSSREFS

Cf. A051802, A051809, A051827.

Sequence in context: A307440 A087912 A308878 * A091102 A323771 A325140

Adjacent sequences:  A051815 A051816 A051817 * A051819 A051820 A051821

KEYWORD

nonn,base,hard

AUTHOR

Dan Hoey, Dec 09 1999

STATUS

approved

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Last modified September 21 00:17 EDT 2019. Contains 327252 sequences. (Running on oeis4.)