Enneadecagonal number | Function to calculate Enneadecagonal number ; Formula for finding nth Enneadecagonal number ; Driver Code
< ? php function nthEnneadecagonal ( $ n ) { return ( 17 * $ n * $ n - 15 * $ n ) / 2 ; } $ n = 6 ; echo $ n , " th ▁ Enneadecagonal ▁ number ▁ : " , nthEnneadecagonal ( $ n ) ; ? >