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
Examples
a(3) = 300 as there are 300 3-digit numbers divisible by 3: 102, 105, ..., 999.
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
Extensions
More terms from Jason Earls, May 26 2001
More terms and a(14) corrected by Jon E. Schoenfield, Dec 02 2021