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 | 3 |
| 2 | 12 |
| 3 | 57 |
| 4 | 306 |
| 5 | 1806 |
| 6 | 11508 |
| 7 | 78147 |
| 8 | 559962 |
| 9 | 4201038 |
| 10 | 32792472 |
| 11 | 264946446 |
| 12 | 2206077804 |
| 13 | 18860908644 |
| 14 | 165050642736 |
| 15 | 1474389557739 |
| 16 | 13413397423482 |
| 17 | 124030117316238 |
| 18 | 1163661348170328 |
| 19 | 11060842687616610 |
| 20 | 106377560784576612 |
| 21 | 1034009073326130876 |