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 | 2 |
| 3 | 12 |
| 4 | 112 |
| 5 | 1450 |
| 6 | 23976 |
| 7 | 482944 |
| 8 | 11472896 |
| 9 | 314061948 |
| 10 | 9734500000 |
| 11 | 336998573296 |
| 12 | 12888244482048 |
| 13 | 539640296743288 |
| 14 | 24552709165722752 |
| 15 | 1206192446775000000 |
| 16 | 63633506348182798336 |
| 17 | 3587991568046845781776 |
| 18 | 215334327830586721473024 |
| 19 | 13705101790650454900938688 |