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 | 5 |
| 3 | 19 |
| 4 | 97 |
| 5 | 581 |
| 6 | 3661 |
| 7 | 26335 |
| 8 | 202049 |
| 9 | 1659817 |
| 10 | 14621941 |
| 11 | 135567851 |
| 12 | 1326672865 |
| 13 | 13624218349 |
| 14 | 146056961597 |
| 15 | 1633376573431 |
| 16 | 18980051829121 |
| 17 | 228677164878545 |
| 18 | 2852155973178469 |
| 19 | 36740599423566787 |
| 20 | 488127224550517601 |
| 21 | 6678832987859315221 |