A051818 Number of n-digit numbers with nonzero multiplicative digital root 7.

1, 3, 14, 86, 666, 6418, 64079, 597445, 5116146, 40671872, 304752986, 2187716324, 15395364971, 110611591118, 866239098731, 7907500662596

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: A087912 A384343 A308878 * A091102 A323771 A325140

Adjacent sequences: A051815 A051816 A051817 * A051819 A051820 A051821

Keyword

nonn,base,hard

Author

Dan Hoey, Dec 09 1999

Status

approved