Each number of the series is 15 multiplied by a prime number i.e., 15 × 11, 15 × 13, 15 × 17, 15 × 19, 15 × 23,.............. So, missing term = 15 × 29 = 435
The terms of the given series are (23 - 1), (33 - 1), (43 - 1 ), (53 - 1), (63 - 1), (73 - 1),.......... So, missing term = (83 - 1) = (512 - 1) = 511.