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 | 6 |
| 2 | 40 |
| 3 | 352 |
| 4 | 4156 |
| 5 | 52488 |
| 6 | 699600 |
| 7 | 9587580 |
| 8 | 134223976 |
| 9 | 1908881900 |
| 10 | 27487869472 |
| 11 | 399822505524 |
| 12 | 5864063067176 |
| 13 | 86607686432616 |
| 14 | 1286742765058960 |
| 15 | 19215358428046176 |
| 16 | 288230376353050696 |
| 17 | 4340410370537249376 |
| 18 | 65588423376053309360 |
| 19 | 994182417449857925988 |