A220491
The smallest n-digit number whose last k digits are divisible by k for k = 1..n.
Original entry on oeis.org
0, 10, 102, 1000, 10000, 102000, 1000300, 10000000, 102000600, 1000000000, 10000108360, 102000060480, 1000006930000, 10000063165960, 102000042276960, 1000000000000000, 10000000141981840, 102000006021375360, 1000000081060819840, 10000000000000000000
Offset: 1
There are ten one-digit numbers divisible by 1, and the smallest is 0, so a(1) = 0.
For two-digit numbers, the ones digit must be divisible by 2 which gives 10 as the smallest to satisfy the requirement. So a(2) = 10.
A220490
The largest n-digit number whose last k digits are divisible by k for k = 1..n.
Original entry on oeis.org
9, 98, 996, 9996, 99960, 999960, 9999780, 99999360, 999999360, 9999999360, 99999951480
Offset: 1
There are ten one-digit numbers divisible by 1 and the largest is 9 so a(1)=9.
For two-digit numbers, the ones digit must make it divisible by 2, which gives 98 as the largest to satisfy the requirement. So a(2)=98.
A221532
The number of n-digit numbers whose last k digits are divisible by k for k = 1..n.
Original entry on oeis.org
10, 45, 150, 756, 1530, 5100, 7301, 38646, 42940, 430263, 391149
Offset: 1
There are ten one-digit numbers divisible by 1 so a(1)=10.
For two-digit numbers, the ones digit must be such that the two-digit number is divisible by 2 which gives 45 numbers, that is, all even numbers from 10 to 98 to satisfy the requirement. So a(2)=45.
Showing 1-3 of 3 results.