Fatto matematico: 1505 is the number of necklaces possible with 6 beads, each being one of 5 colors.
Trivia: 1505 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: February 13th is the day in 1984 that Konstantin Chernenko succeeds the late Yuri Andropov as general secretary of the Communist Party of the Soviet Union.