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 | 15 |
| 3 | 111 |
| 4 | 3936 |
| 5 | 28320 |
| 6 | 999855 |
| 7 | 7193295 |
| 8 | 253959360 |
| 9 | 1827068736 |
| 10 | 64504677711 |
| 11 | 464068265775 |
| 12 | 16383934179360 |
| 13 | 117871512438240 |
| 14 | 4161454776879855 |
| 15 | 29938900091047311 |
| 16 | 1056993129393303936 |
| 17 | 7604362751613578880 |
| 18 | 268472093411122320015 |
| 19 | 1931478200009757988335 |