#35 of a series that is never used. An abandoned car park. Campbell Street, Hobart, October 2010. Who knew that number 35 was so important? Did you know that…? 35 is the sum of the first five triangular numbers, making it a tetrahedral number. 35 is a centered cube number, a pentagonal number and a pentatope number. 35 is a highly cototient number, since there are more solutions to the equation x - φ(x) = 35 than there are for any other integers below it except 1. There are 35 free hexominoes, the polyominoes made from six squares. Since the greatest prime factor of 352 + 1 = 1226 is 613, which is obviously more than 35 twice, 35 is a Størmer number. All I know is Rule 35 of the Internet!