Driver Code
int main ( ) { int n = 5 ; cout << n << " th ▁ centered ▁ decagonal " << " number : ▁ " ; cout << centereddecagonalnum ( n ) ; cout << endl ; n = 9 ; cout << n << " th ▁ centered ▁ decagonal " << " number : ▁ " ; cout << centereddecagonalnum ( n ) ; return 0 ; }