+ import std.math;
  import std.typecons;
- import std.math;
  /*
  Everyone knows Fibonacci sequence, it was studied deeply by mathematicians in 
-     the last couple centuries. However, what people don't know is Tribonacci sequence.
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+ the last couple centuries. However, what people don't know is Tribonacci sequence.
-     Tribonacci sequence is defined by the recurrence:
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+ Tribonacci sequence is defined by the recurrence:
-     tri(1) = 3
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+ tri(1) = 3
-     tri(n) = 1 + n / 2, if n is even.
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+ tri(n) = 1 + n / 2, if n is even.
-     tri(n) =  tri(n - 1) + tri(n - 2) + tri(n + 1), if n is odd.
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+ tri(n) =  tri(n - 1) + tri(n - 2) + tri(n + 1), if n is odd.
-     For example:
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+ For example:
-     tri(2) = 1 + (2 / 2) = 2
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+ tri(2) = 1 + (2 / 2) = 2
-     tri(4) = 3
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+ tri(4) = 3
-     tri(3) = tri(2) + tri(1) + tri(4)
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+ tri(3) = tri(2) + tri(1) + tri(4)
-            = 2 + 3 + 3 = 8 
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+        = 2 + 3 + 3 = 8 
-     You are given a non-negative integer number n, you have to a return an array of the 
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+ You are given a non-negative integer number n, you have to a return an array of the 
-     first n + 1 numbers of the Tribonacci sequence.
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+ first n + 1 numbers of the Tribonacci sequence.
-     Examples:
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+ Examples:
-     >>> tri(3L)
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+ >>> tri(3L)
-     [1L, 3L, 2L, 8L]
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+ [1L, 3L, 2L, 8L]
-     
  */
  long[] tri(long n)