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 | 16 |
| 4 | 135 |
| 5 | 944 |
| 6 | 4814 |
| 7 | 26435 |
| 8 | 158761 |
| 9 | 978044 |
| 10 | 5847896 |
| 11 | 34112584 |
| 12 | 200686378 |
| 13 | 1192024482 |
| 14 | 7093151801 |
| 15 | 42038865123 |
| 16 | 248625856115 |
| 17 | 1472077262971 |
| 18 | 8724918986240 |
| 19 | 51715149361624 |
| 20 | 306384777098954 |
| 21 | 1814848220902299 |
| 22 | 10751681585808618 |
| 23 | 63702848673263049 |