M+++"=1asmBa++'=0%'Va'a:1a!+|&=%"Vb"a0a0#~a$@"Vb0'
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Explanation:
M is similar to python's eval in recursiva. So, basically. we are building a string and evaluating it using M. Let's say we input 20 the string(everything following M) will be: =1a:1!+|&=%20a0a0#~a$@20.
This is a recursiva function with parameter 20 passed into it and is recursive. The tail condition is given in =1a:1 which is saying for value of 1 simply returns 1. For other conditions we simply add the current number if it perfectly divides 20(The number we are interested in) else add 0 +|&=%"Vb"a0a0. The #~a$ part is making a call to the same function but with one decremented value ~a since ~ is minus-one operator.
smBa++'=0%'Va'a:a!0' - Input to a; 20
s - sum up; 42
m - map with; [1, 0, 3, 0, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 15]
Ba - Range; [1,2..20]
++'=0%'Va'a:a!0' - function, evaluates to 0 if param cannot divide a; [20]
