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 | 4 |
| 4 | 13 |
| 5 | 29 |
| 6 | 106 |
| 7 | 331 |
| 8 | 1222 |
| 9 | 4390 |
| 10 | 16588 |
| 11 | 62865 |
| 12 | 243217 |
| 13 | 947711 |
| 14 | 3732800 |
| 15 | 14801687 |
| 16 | 59103268 |
| 17 | 237305379 |
| 18 | 957738244 |
| 19 | 3882631356 |
| 20 | 15804400624 |