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 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 66 |
| 6 | 420 |
| 7 | 3200 |
| 8 | 27144 |
| 9 | 258705 |
| 10 | 2704592 |
| 11 | 30898506 |
| 12 | 381922380 |
| 13 | 5090938955 |