Icositrigonal Number | Function to find N - th Icositrigonal number ; Formula to calculate nth Icositrigonal number ; Driver code
function Icositrigonal_num ( n ) { return ( 21 * n * n - 19 * n ) / 2 ; } let n = 3 ; document . write ( Icositrigonal_num ( n ) + " " ) ; n = 10 ; document . write ( Icositrigonal_num ( n ) ) ;