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 | 5 |
| 3 | 39 |
| 4 | 345 |
| 5 | 3512 |
| 6 | 38431 |
| 7 | 451620 |
| 8 | 5587237 |
| 9 | 72275004 |
| 10 | 968509140 |
| 11 | 13361356169 |
| 12 | 188704259571 |
| 13 | 2716467168169 |
| 14 | 39716842554828 |
| 15 | 588125693790055 |
| 16 | 8800638181341593 |
| 17 | 132838773216409675 |
| 18 | 2019626662710709088 |
| 19 | 30891440565153652705 |
| 20 | 474899505740289874276 |