Agreed

better use an enumerate's argument for the start index

This is an awesome little tidbit of information.

@Unnamed, @Blind4Basics: There is a Guido's article about List Comprehensions and Generator Expressions advantages - http://python-history.blogspot.com/2010/06/from-list-comprehensions-to-generator.html
But yeah, it's more about comparison between LCs and (map with lambda). Thanks for correcting me

@Rishat Nuriev:

see the fork: no meaningful difference between the three versions (500 tests on one input of size 500x500). The 3 versions perform about the same. Sometimes one is faster than the others, but not always the same one. You'd need something far more precise to actually see any consistent difference.

@Unnamed: you don't use lambda in there, so no overhead on this side (which is often what is slowing this kind of approach, I believe).

2 Usually true.
1 Who told you that? I know Python folks don't like lambdas, but I haven't heard anything about map. One function call is easier to read than an expression where a new variable is introduced for no reason.

1. It's better to use List Comprehensions instead of (map/filter) when possible
2. It's better to use Generator Expressions instead of List Comprehensions when possible

I'm sure this should be best practice

I think that we don't need to create a dictionary, a list is enough
Also no need to check if number is in the dict (easier to check if it's less or equal than 100)