Tribonacci Numbers in C++

Here we will see how to generate the Tribonacci numbers using C++. The Tribonacci numbers are similar to the Fibonacci numbers, but here we are generating a term by adding three previous terms. Suppose we want to generate T(n), then the formula will be like below −

T(n) = T(n - 1) + T(n - 2) + T(n - 3)

The first few numbers to start, are {0, 1, 1}

Algorithm

tribonacci(n):
Begin
   first := 0, second := 1, third := 1
   print first, second, third
   for i in range n – 3, do
      next := first + second + third
      print next
      first := second
      second := third
      third := next
   done
End

Example

#include<iostream>
using namespace std;
long tribonacci_gen(int n){
   //function to generate n tetranacci numbers
   int first = 0, second = 1, third = 1;
   cout << first << " " << second << " " << third << " ";
   for(int i = 0; i < n - 3; i++){
      int next = first + second + third;
      cout << next << " ";
      first = second;
      second = third;
      third = next;
   }
}
main(){
   tribonacci_gen(15);
}

Output

0 1 1 2 4 7 13 24 44 81 149 274 504 927 1705