[Learning] 3 hours for one simple exercise

[perfringo]

Sum of which numbers squares is needed?

>>> list(range(1, 20, 4))
[1, 5, 9, 13, 17]
>>> list(range(1, 20, 5))
[1, 6, 11, 16]

You can use built-in help to understand how range works:

>>> help(range)

Help on class range in module builtins:

class range(object)
 |  range(stop) -> range object
 |  range(start, stop[, step]) -> range object
 |  
 |  Return an object that produces a sequence of integers from start (inclusive)
 |  to stop (exclusive) by step.  range(i, j) produces i, i+1, i+2, ..., j-1.
 |  start defaults to 0, and stop is omitted!  range(4) produces 0, 1, 2, 3.
 |  These are exactly the valid indices for a list of 4 elements.
 |  When step is given, it specifies the increment (or decrement).
 |  
/.../