The Online Encyclopedia of Integer Sequences has been around for a long, long time and yet it stays handy to lookup that number sequence that shows up in your research data. Born from the AT&T research labs, back when they were still the best
In fact, it is handy to look up your phone number, or date of birth. In my case both yielded a list of papers that references the sequences!
Q: What is the purpose of the OEIS?
A: The main purpose is to allow mathematicians or other scientists to find out if some sequence that turns up in their research has ever been seen before.
If it has, they may find that the problem they’re working on has already been solved, or partially solved, by someone else.
Or they may find that the sequence showed up in some other situation,
which may show them an unexpected relationship between their problem and something else.
Another purpose is to have an easily accessible database of important, but difficult to compute, sequences.
For example, if you’re testing some conjecture about Mersenne primes, you can look up the ones that are known (see A000043),
rather than spending years recomputing them.