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a(n) is the number of n-digit multiples of n.
4

%I #21 Aug 18 2024 02:01:20

%S 10,45,300,2250,18000,150000,1285714,11250000,100000000,900000000,

%T 8181818181,75000000000,692307692307,6428571428572,60000000000000,

%U 562500000000000,5294117647058823,50000000000000000,473684210526315789,4500000000000000000,42857142857142857143

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

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

%F 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

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

%K nonn,base,easy

%O 1,1

%A _Amarnath Murthy_, May 23 2001

%E More terms from _Jason Earls_, May 26 2001

%E More terms and a(14) corrected by _Jon E. Schoenfield_, Dec 02 2021