Consider the quadratic $x^2+x+1$. By substituting $x=1,2,3,\cdots$ we can form a sequence $$ x^2+x+1 : 3, 7, 13, 21, 31, \cdots $$
Issue 2
The marvellous formula of Euler, $V-E+F=2$, can yield interesting results other than that concerning the Platonic Solids.
Issue 3
Several thousand years ago, magic squares were being used by Indian astrologers in their calculations of horoscopes.