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 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 31 |
| 6 | 246 |
| 7 | 1296 |
| 8 | 10774 |
| 9 | 83238 |
| 10 | 788820 |
| 11 | 6835170 |
| 12 | 81364944 |
| 13 | 848378532 |
| 14 | 11423650616 |
| 15 | 156289508025 |
| 16 | 2380629720720 |
| 17 | 33284133330760 |
| 18 | 605934954285120 |
| 19 | 9708364832948820 |
| 20 | 190330953679235040 |
| 21 | 3715069138923234960 |
| 22 | 77101583995105472880 |
| 23 | 1506549946554254503440 |