A061772 a(n) is the number of n-digit multiples of n.

10, 45, 300, 2250, 18000, 150000, 1285714, 11250000, 100000000, 900000000, 8181818181, 75000000000, 692307692307, 6428571428572, 60000000000000, 562500000000000, 5294117647058823, 50000000000000000, 473684210526315789, 4500000000000000000, 42857142857142857143

Offset

1,1

Links

Table of n, a(n) for n=1..21.

Formula

a(n) = floor((9*10^(n-1)/n) or floor((9*10^(n-1))/n) + 1.

a(1)=10; a(n) = floor((10^n - 1)/n) - floor((10^(n-1) - 1)/n) for n > 1. - Jon E. Schoenfield, Dec 02 2021

Example

a(3) = 300 as there are 300 3-digit numbers divisible by 3: 102, 105, ..., 999.

Crossrefs

Sequence in context: A264553 A278641 A219709 * A032165 A124174 A264414

Adjacent sequences: A061769 A061770 A061771 * A061773 A061774 A061775

Keyword

nonn,base,easy

Author

Amarnath Murthy, May 23 2001

Extensions

More terms from Jason Earls, May 26 2001

More terms and a(14) corrected by Jon E. Schoenfield, Dec 02 2021

Status

approved