Use recursion to calculate the Fibonacci sequence value of a specified number of digits

Yesterday, I encountered a question like 1, 1, 2, 3, 5, 8, 13, 21.... What is the value of 30th?CodeThe implementation is as follows:

 1       //  30th, 13, 21 ...... what is?  2       //  Use recursion to calculate the Fibonacci sequence value of a specified number of digits  3       //  Fn = f (n-1) + f (n-2)  4       Public   Static   Int Getfibonaccinumber ( Int Index)  5   {  6           If (Index < 0 | Index = 0 ) Throw   New Exception ( "  The parameter cannot be less than or equal to 0.  "  );  7           If (Index <= 2 )  8   {  9               Return   1  ;  10   }  11           Else  12   {  13               Return Getfibonaccinumber (index- 1 ) + Getfibonaccinumber (index-2  );  14   }  15 }

 

Additional reading

Wikipedia: Fibonacci Series