There is a massive problem with all-multiples-of-two: it expects 2, 4, 6, ... instead of 0, 2, 4, ... (0 is a multiple of 2 too), and it only checks the first 2 values so [2, 4] will also pass the tests.

The kata doesn't explain what the functions required to be implemented are expected to do.

This issue could be clearer

I'm so sorry!

Please use spoiler flag next time, your post was visible in the homepage.

Seems you guys find an "a" number in the array that gives the formula answer.

I looped both "a" and "b" and gave timeout error :)

a * b + b

=> a * b + 1 * b

=> b * (a + 1)

// b is the common factor here.

a*b + b = 0

"b" goes in front of the brackets, causing the quation to look like:

b*(a+1) = 0

Thereforfe, ab+b = b(a+1)

How did we go from a * b + b to b * (a + 1) ??

This fails at least for n equals 5, 15, 32, 90, 189, 527, 1104, 3074, 6437, 17919 and 37520, because it doesn't check a != b

No random tests.

The description explains nothing at all.

It's live for me.

nice, this is arithmetic progression, but I forget it

thank you I like this