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 | 1 |
| 2 | 5 |
| 3 | 54 |
| 4 | 940 |
| 5 | 22917 |
| 6 | 722530 |
| 7 | 28009490 |
| 8 | 1289854644 |
| 9 | 68827561580 |
| 10 | 4176770296181 |
| 11 | 284087018905946 |
| 12 | 21406395137288400 |
| 13 | 1770085307452770344 |
| 14 | 159359206078637624790 |
| 15 | 15516776721991034328250 |