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 | 12 |
| 4 | 54 |
| 5 | 276 |
| 6 | 1574 |
| 7 | 9916 |
| 8 | 68394 |
| 9 | 512671 |
| 10 | 4150148 |
| 11 | 36086135 |
| 12 | 335447341 |
| 13 | 3319876281 |
| 14 | 34853551700 |
| 15 | 386889999296 |
| 16 | 4527701024471 |
| 17 | 55715658165361 |
| 18 | 719205555167707 |
| 19 | 9717733698168073 |
| 20 | 137168409543673446 |
| 21 | 2018981393006166050 |
| 22 | 30936712227446490134 |