Fatto generale: 1555 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1555 is the largest n so that Q(vn) has class number 4.
Trivia: 1555 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: April 3rd is the day in 1981 that the Osborne 1, the first successful portable computer, is unveiled at the West Coast Computer Faire in San Francisco.