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) |
|---|---|
| 1 | 3 |
| 2 | 20 |
| 3 | 93 |
| 4 | 390 |
| 5 | 1530 |
| 6 | 5768 |
| 7 | 21142 |
| 8 | 75908 |
| 9 | 268282 |
| 10 | 936480 |
| 11 | 3236244 |
| 12 | 11091230 |
| 13 | 37747805 |
| 14 | 127710397 |
| 15 | 429872190 |
| 16 | 1440515533 |
| 17 | 4808357581 |
| 18 | 15994483255 |
| 19 | 53039715042 |
| 20 | 175399135922 |
| 21 | 578584268700 |
| 22 | 1904232092224 |
| 23 | 6254245258553 |