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 | 3 |
| 3 | 14 |
| 4 | 78 |
| 5 | 508 |
| 6 | 3796 |
| 7 | 32048 |
| 8 | 301872 |
| 9 | 3139680 |
| 10 | 35746080 |
| 11 | 442258560 |
| 12 | 5909028480 |
| 13 | 84802072320 |
| 14 | 1301090515200 |
| 15 | 21253339699200 |
| 16 | 368281038182400 |
| 17 | 6747621163315200 |
| 18 | 130338926671564800 |
| 19 | 2647326900234240000 |
| 20 | 56404832240977920000 |