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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 20 |
| 5 | 125 |
| 6 | 1070 |
| 7 | 11465 |
| 8 | 146600 |
| 9 | 2173625 |
| 10 | 36633050 |
| 11 | 691362125 |
| 12 | 14440672700 |
| 13 | 330674815925 |
| 14 | 8236528396550 |
| 15 | 221694575073425 |
| 16 | 6411977928702800 |
| 17 | 198310761891213425 |
| 18 | 6530970632654064050 |