163877

10 = n
11 = n+1
12 = n+2 = 3n + 3
3n + 3 = (multiple of 3) + 3

10 = n
11= n + 1
12 = n + 2
13 = n + 3
14 = n + 4 = 5n + 10
5n + 10 = (multiple of 5) + 10

Any odd number will always be added a multiple of itself eg.(multiple of 3) + 3, (multiple of 5) + 10, (multiple of 7) = 21.
But as for even numbers it will never be added a multiple of itself eg. (multiple of 2) + 1, (multiple of 4) + 6, (multiple of 6) + 21