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

Author

Dan Hoey, Dec 09 1999

Keywords

• nonn
• base
• hard

References

• William Mayne, sci.math, Jun 15 1991

Crossrefs

Cf. A051802, A051804, A051822.

Formula

# { i : 10^(n-1) < i < 10^n and A051802(i)=2 }