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 | 6 |
| 3 | 20 |
| 4 | 54 |
| 5 | 275 |
| 6 | 556 |
| 7 | 1965 |
| 8 | 3498 |
| 9 | 10206 |
| 10 | 43453 |
| 11 | 68135 |
| 12 | 242812 |
| 13 | 536104 |
| 14 | 785437 |
| 15 | 1644136 |
| 16 | 4712040 |
| 17 | 12760906 |
| 18 | 17591088 |
| 19 | 44736332 |
| 20 | 81493581 |
| 21 | 109311863 |
| 22 | 257863391 |
| 23 | 448980978 |
| 24 | 1007135164 |
| 25 | 2840344772 |
| 26 | 4695605081 |
| 27 | 6015397025 |
| 28 | 9803584533 |
| 29 | 12473509636 |
| 30 | 20063812526 |