Driver Code
$ n = 6 ; echo $ n , " th ▁ centered " , " ▁ octagonal ▁ number ▁ : ▁ " ; echo cen_octagonalnum ( $ n ) ; echo " STRNEWLINE " ; $ n = 11 ; echo $ n , " th ▁ centered " , " ▁ octagonal ▁ number ▁ : ▁ " ; echo cen_octagonalnum ( $ n ) ; ? >