Wittgenstein's philosophy of mathematics might be interesting to you. His description of calculation as a linguistic process should settle the issue if you buy it.
Edit: just found this related item on HN, a math prof examining the nature of a proof: http://profkeithdevlin.org/2014/11/24/what-is-a-proof-really...
By the way, older people who share the characteristics of being only lightly acculturated (i.e. eccentric) share the relevant characteristics with children and may be able to learn things like languages with childlike speed. Hence, I believe, PG's observation that startup founders of any age tend to be weird, quirky, or poorly socialized in various ways.
all cultural, mutable, consensus based concepts are more easily learned as a child
There are many "hobbies" that have a cultural component. It helps to learn these earlier, because it removes cognitive overhead during later studies. But its simply not true that children are better at learning everything. They are hard-wired for language tho. Plenty of other things they are un/der developed for.
I have recently found tools that are mostly used for learning natural languages are also useful for learning programming languages. Computer flash card programs, like Anki, are effective at memorizing a vocabulary efficiently. Just like real flash cards, you put an English word or definition on one side, and the word or phrase on the other side.
So as I've been going through a Coursera on the R programming language, every time the instructor explains a new function or way of doing something, I put it in an Anki flash card. I haven't been doing it for long enough to be certain, but so far I think it's been pretty effective. Because 90% of the work of learning a programming language is just like a natural language; the vocabulary and grammar.
You could also use this to learn mathematical notation, but that's only a small part of it. I have yet to find any use for this system in my other Coursera course on logic.