A051816 Number of n-digit numbers with nonzero multiplicative digital root 5.

1, 7, 58, 422, 2872, 19772, 142418, 1096582, 9040811, 78452199, 699839588, 6297456806, 56804155533, 517737762700, 4839960759976, 46837953974511

Offset: 1

Author

Dan Hoey, Dec 09 1999

Keywords

• nonn
• base
• hard

References

• William Mayne, sci.math, Jun 15 1991

Crossrefs

Cf. A051802, A051807, A051825.

Formula

# { i : 10^(n-1) < i < 10^n and A051802(i)=5 }