Fibonacci day, i.e. the date today, i.e. 11/23, represents the first 4 numbers of the Fibonacci sequence. The Fibonacci sequence starts with 1, 1, and the then every number after is the sum of the previous two numbers in the sequence, so the next number is 1+1=2, then 2+1=3, so the first four numbers are: 1, 1, 2, 3 -- corresponding with 11/23. In 37 years it will be 11/23/58, so we'll have the fifth number, 3+2=5, and the sixth number, 5+3=8. In 3792 years, it will be 11/23/5813, so we'll have the fifth and sixth numbers and the seventh, 5+8=13.