Sum of the first N terms of the series 2 , 6 , 12 , 20 , 30. ... | Function to calculate the sum ; number of terms to be included in the sum ; find the Sn
< ? php function calculateSum ( $ n ) { return $ n * ( $ n + 1 ) / 2 + $ n * ( $ n + 1 ) * ( 2 * $ n + 1 ) / 6 ; } $ n = 3 ; echo " Sum = " ? >