Numbers on the BTC blockchain already:
1D: 1, 2 ,3 ,5 ,8 ,9
2D: 13, 18, 21, 33, 34, 55, 62, 69, 89
3D: 000, 144, 233, 377, 456, 610, 666, 888, 987
Prime numbers and the Fibonacci sequence seem to be the most important. There are also registered Fibonacci primes!
@OrdDirectory