text: Sum of first n term of Series 3 , 5 , 9 , 17 , 33. ... | C # program to find sum of first n terms ; Sn = n * ( 4 * n * n + 6 * n - 1 ) / 3 ; Driver Code ; number of terms to be included in sum ; find the Sn
code: using System ; class GFG { static int calculateSum ( int n ) { return ( ( int ) Math . Pow ( 2 , n + 1 ) + n - 2 ) ; } public static void Main ( ) { int n = 4 ; Console . WriteLine ( " Sum ▁ = ▁ " + calculateSum ( n ) ) ; } }