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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 31 |
| 5 | 248 |
| 6 | 2382 |
| 7 | 27233 |
| 8 | 359800 |
| 9 | 5364193 |
| 10 | 88622485 |
| 11 | 1602171855 |
| 12 | 31410476113 |
| 13 | 663240471075 |
| 14 | 15001046054183 |
| 15 | 361775504849332 |
| 16 | 9266474332849318 |
| 17 | 251217335356943672 |
| 18 | 7186461542458525108 |
| 19 | 216332059500870350414 |
| 20 | 6835872042063656823802 |