As you know, a prime number is any positive integer, other than 1, which has exactly two distinct factors (itself and 1). Thus the set of primes starts $2,3,5,7,11, \ldots, $
Many of the articles in Parabola pose problems which invite the reader to invent original solutions. But, in the absence of a helpful hint, how does one set about arriving at such a solution?
In Problem O230 I noticed that those positions where the second player can force a wing are all Fibonacci numbers.
J231 A man goes to an auction with \$100 and buys exactly 100 animals.
J221 Find a 2-digit number $AB$ such that $(AB)^2 - (BA)^2$ is a perfect square.