Joe Auslander turns 90 on September 10, 2020.
In this space, let's share memories, photographs, and stories about Joe--across nine decades. Brief and longer reminiscences or anecdotes, humorous and serious, are all equally welcome. Although in our strange quarantined era, we can't have a large face-to-face celebration, we can gather together in this virtual space to reflect and celebrate.
For the mathematically inclined among Joe's friends, any mathematical observations on the number "90" would be gratefully received.
To start things off:
--If I correctly remember the lessons of my youth, 90 is one of the only five known unitary perfect numbers because it is an integer which is the sum of its positive proper unitary divisors, (not including the number itself) That is to say, 90 = 1 + 2 + 5 + 9 + 10 + 18 + 45! Joe had his first unitary perfect number birthday in 1938 at age 6, but hasn't had a unitary perfect number birthday since 1990, at age sixty. I don't believe he will have another such birthday until he turns 87,360 in the year 89, 290!
--90 degrees constitutes a "right" angle, although perhaps Dad, as a left-handed progressive, would be more appreciative of a "left" angle?
--The number ninety, that is to say nine times ten, (3x3x) x (2x5), can be expressed as three times the product of the three lowest primes (2x3x5).
Anything else about 90 of note?
Please send along all recollections, images, and other appropriate materials about Joe as the spirit moves you!
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