An obscure passage from Plutarch’s De Stoicorum repugnantiis:
But now he [Chrysippus] says himself that the number of conjunctions produced by means of ten assertibles exceeds a million, though he had neither investigated the matter carefully by himself nor sought out the truth with the help of experts. [...] Chrysippus is refuted by all the arithmeticians, among them Hipparchus himself who proves that his error in calculation is enormous if in fact affirmation gives 103049 conjoined assertibles and negation 310952.
Hipparchus flourished in the second century BC. Today we would probably call him a mathematical physicist. Plutarch wrote some two hundred fifty years later.
In 1870, the mathematician Friedrich Wilhelm Karl Ernst Schrder showed that the number of possible ways to bracket a row of ten symbols, e.g.
(AA)(AAA(AA)A)(AA)and not including singletons or the whole row, was equal to 103049. This is sometimes written as s(10) = 103049.
In 1994, David Hough at George Washington University noticed that these two numbers were the same.
In 1998, Habseiger, Kazarian and Lando noticed that Plutarch's second number, 310952, was very close to half the sum of the tenth and eleventh of Schrder's numbers: (s(10) + s(11))/2 = 310954.
The modern branch of mathematics which deals with enumerating combinations is called combinatorics. It was once thought that the ancient Greeks had no interest in the subject.
(Hat-tip to Alexandre Borovik, who comes from the opposite end of the Tea Road as some of my forebears. The passage from Plutarch comes from F. Acerbi, "On the Shoulders of Hipparchus: A Reappraisal of Ancient Greek Combinatorics", Arch. Hist. Exact Sci. 57 (2003) 465-502.)