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 | 1 |
| 1 | 6 |
| 2 | 30 |
| 3 | 210 |
| 4 | 1260 |
| 5 | 7770 |
| 6 | 46410 |
| 7 | 279930 |
| 8 | 1678320 |
| 9 | 10077480 |
| 10 | 60458370 |
| 11 | 362797050 |
| 12 | 2176734420 |
| 13 | 13060694010 |
| 14 | 78363884130 |
| 15 | 470184976590 |
| 16 | 2821108227840 |
| 17 | 16926659444730 |
| 18 | 101559946544280 |
| 19 | 609359740010490 |
| 20 | 3656158379595540 |
| 21 | 21936950640097710 |
| 22 | 131621703479470050 |