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A051820 Number of n-digit numbers with nonzero multiplicative digital root 9. 1
1, 4, 25, 180, 1640, 17678, 213761, 2572363, 28717151, 295374892, 2863710220, 27059835840, 257084859669, 2498594395926, 24825380748687, 249116120158421 (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)=9 }

CROSSREFS

Cf. A051802, A051811, A051829.

Sequence in context: A213608 A324169 A213231 * A246539 A166697 A054368

Adjacent sequences:  A051817 A051818 A051819 * A051821 A051822 A051823

KEYWORD

nonn,base,hard

AUTHOR

Dan Hoey, Dec 09 1999

STATUS

approved

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Last modified November 20 05:07 EST 2019. Contains 329323 sequences. (Running on oeis4.)