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 | 17 |
| 4 | 73 |
| 5 | 381 |
| 6 | 2347 |
| 7 | 16701 |
| 8 | 134993 |
| 9 | 1222873 |
| 10 | 12279251 |
| 11 | 135425553 |
| 12 | 1627809401 |
| 13 | 21183890469 |
| 14 | 296773827547 |
| 15 | 4453511170517 |
| 16 | 71275570240417 |
| 17 | 1211894559430065 |
| 18 | 21816506949416611 |
| 19 | 414542720924028441 |
| 20 | 8291224789668806345 |
| 21 | 174120672081098057341 |