I don't understand the description

snake case +1

approved

Haskell translation

See above Issue.

( JS )

BigInt output format should be specified.

Tests should not accept Numbers, just BigInts, especially example tests.

Hint: use memoization

Nice kata but you should include random numbers atleast upto 0<=n<=10^5

You may read about the difference between a recursive approach and an iterative one.

I pass random tests but get Execution Timed Out (12000 ms) when trying to attempt, any advice?