|
COMMENTS
|
There are total 224 numbers and 224246090, 632258960, 824791960, 851750490, and 904719030 are the only 9-digit numbers to satisfy the requirement.
|
|
EXAMPLE
|
There are five one-digit numbers divisible by the first prime so a(1)=5.
For two-digit numbers, the second digit must make it divisible by 3 which gives 15 numbers: 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 84, 90, 96 to satisfy the requirement. So a(2)=15.
|