Program to find N | Function to find n - th number in series made of 3 and 5 ; create an array of size ( n + 1 ) ; If i is odd ; main function
function prletNthElement ( n ) { let arr = Array ( n + 1 ) . fill ( 0 ) ; arr [ 1 ] = 3 ; arr [ 2 ] = 5 ; for ( i = 3 ; i <= n ; i ++ ) { if ( i % 2 != 0 ) arr [ i ] = arr [ i / 2 ] * 10 + 3 ; else arr [ i ] = arr [ ( i / 2 ) - 1 ] * 10 + 5 ; } return arr [ n ] ; } let n = 6 ; document . write ( prletNthElement ( n ) ) ;