Find the highest power ( stored in exp ) ' ▁ ▁ of ▁ allPrimes [ i ] ▁ that ▁ divides ▁ n ▁ using ▁ ▁ Legendre ' s formula .
$ exp = 0 ; while ( $ p <= $ n ) { $ exp = $ exp + ( int ) ( $ n / $ p ) ; $ p = $ p * $ allPrimes [ $ i ] ; }