Cramér's conjecture

Etymology
Formulated by the Swedish mathematician Harald Cramér in 1936.

Proper noun

 * 1)  An estimate for the size of gaps between consecutive prime numbers, stating that $$p_{n+1}-p_n=O((\log p_n)^2)$$, where pn denotes the nth prime number, O is big O notation, and log is the natural logarithm.