A051813 Number of n-digit numbers with nonzero multiplicative digital root 2.

1, 15, 208, 2389, 24845, 243697, 2348885, 22837227, 226507501, 2285904554, 23239957877, 235731610792, 2372897841904, 23686630752065, 235058927877399, 2327977363798607

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)=2 }

Crossrefs

Cf. A051802, A051804, A051822.

Sequence in context: A078265 A089138 A271333 * A280160 A239991 A274563

Adjacent sequences: A051810 A051811 A051812 * A051814 A051815 A051816

Keyword

nonn,base,hard

Author

Dan Hoey, Dec 09 1999

Status

approved