[saltvedt]

"The Bailey–Borwein–Plouffe formula (BBP formula) is a spigot algorithm for computing the nth binary digit of the mathematical constant π using base-16 representation. The formula can directly calculate the value of any given digit of π without calculating the preceding digits. (...) Though the BBP formula can directly calculate the value of any given digit of π with less computational effort than formulas that must calculate all intervening digits, BBP remains linearithmic (O(n log n)), whereby successively larger values of n require increasingly more time to calculate; that is, the "further out" a digit is, the longer it takes BBP to calculate it, just like the standard π-computing algorithms."

https://en.wikipedia.org/wiki/Bailey%E2%80%93Borwein%E2%80%9...