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 | 11 |
| 4 | 51 |
| 5 | 266 |
| 6 | 1540 |
| 7 | 9681 |
| 8 | 65291 |
| 9 | 468401 |
| 10 | 3551693 |
| 11 | 28327029 |
| 12 | 236731183 |
| 13 | 2066583601 |
| 14 | 18796448581 |
| 15 | 177735656083 |
| 16 | 1743920667437 |
| 17 | 17725856560839 |
| 18 | 186366309301259 |
| 19 | 2024042644283702 |
| 20 | 22679125592930412 |
| 21 | 261873356070694571 |