That seems more just very resource requiring than hard to do, in a modern world with computers? I get that these were ridiculous to find around 1900 when they were discovered and you had to find them without computers to do the calculations.
“Resource requiring” and “hard to do” are kind of the same in math’s terms. Most unsolved math problems are either because we lack the resources, we lack observation (in case of phisics) or we lack both.
hat useful purpose does these Dedekind numbers have? Nothing, just like when lasers were first discovered (now we use them for medical and tech purposes)