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 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 53 |
| 5 | 211 |
| 6 | 938 |
| 7 | 4582 |
| 8 | 24349 |
| 9 | 139671 |
| 10 | 858745 |
| 11 | 5628789 |
| 12 | 39145021 |
| 13 | 287667582 |
| 14 | 2226033629 |
| 15 | 18082308403 |
| 16 | 153770703339 |
| 17 | 1365631349757 |
| 18 | 12638233544989 |
| 19 | 121640399661294 |
| 20 | 1215438543434225 |
| 21 | 12587691428792115 |