One can take the view that the topic is becoming too miseellaneous in nature-bestowing names on rather arbitrarily defined classes of numbers does not of its own accord make them interesting. should know when to stop. That said, it is worth appreciating that the underlying strategies used to tackle these new questions a yet reminiscent of Euclid and Euler showed us in relation to perfect numbers. You will recall that what Euclid proved was that if a Mersenne number was prime then another number was even and perfect. Euler then proved conversely that all even perfect numbers arise from this approach. In the 9th century, the Persian mathematician Thabit ibn Qurra introduced for any number triple of numbers which, if all prime, allowed the construetion of an amicable pair. Thabit's construction was generalized further by Euler in the 18th century, but even this enhanced formulation only seems to yield a few amicable pairs and there are many amicable pairs that do not arise from this construction. (There are now nearly 12 million known pairs of amicable numbers) In modern times, a similar approach by Kravitz gives a construction of weird numbers from certain numbers should they happen to be prime, and this formula has successfully found a very large weird number with more than fifty digits.