在 haskell 中创建具有多个条件的列表

Question

Define the sequence (bn)n=1,2,… such that bn=3 when n is divisible by 3, and bn=4(n+1)^2 in other cases. Define a function that for an argument n creates the list of n initial numbers of the sequence (bn)n=1,2,….

so far I have two lists with condition 1 and condition 2:
divisible3 n = [x | x <- [1..n], x `mod` 3 == 0]
notdivisible3 n = [x*x*4+8*x+4 | x <- [1..n], x `mod` 3 /= 0]
I want it to be one list like:
list n = [x | x <- [1..n], condition1, condition 2]

Answer 1

You should write an if... then... else... in the "yield" part of the list comprehension, not a filter. So something like:

list n = [ if n `mod` 3 == 0 then … else … | x <- [1..n]]

where I leave the … parts as an exercise.