This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 99 |
| 5 | 785 |
| 6 | 7151 |
| 7 | 73097 |
| 8 | 827501 |
| 9 | 10295549 |
| 10 | 140100323 |
| 11 | 2077648871 |
| 12 | 33466994639 |
| 13 | 583535328293 |
| 14 | 10971899911703 |
| 15 | 221571516903233 |
| 16 | 4786126571515961 |
| 17 | 110142864494603313 |
| 18 | 2690257065904106571 |
| 19 | 69500954207702580927 |
| 20 | 1893141166438848208747 |
| 21 | 54217997416999007587201 |