- import std.typecons;
  import std.math;
  /*
   Implement the function f that takes n as a parameter,
-     and returns an array of size n, such that the value of the element at index i is the factorial of i if i is even
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+ and returns an array of size n, such that the value of the element at index i is the factorial of i if i is even
-     or the sum of numbers from 1 to i otherwise.
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+ or the sum of numbers from 1 to i otherwise.
-     i starts from 1.
? ----

+ i starts from 1.
-     the factorial of i is the multiplication of the numbers from 1 to i (1 * 2 * ... * i).
? ----

+ the factorial of i is the multiplication of the numbers from 1 to i (1 * 2 * ... * i).
-     Example:
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+ Example:
-     >>> f(5L)
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+ >>> f(5L)
-     [1L, 2L, 6L, 24L, 15L]
? ----

+ [1L, 2L, 6L, 24L, 15L]
-     
  */
  long[] f(long n)