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 | 4 |
| 3 | 28 |
| 4 | 272 |
| 5 | 3369 |
| 6 | 50816 |
| 7 | 903856 |
| 8 | 18522624 |
| 9 | 429746905 |
| 10 | 11135257600 |
| 11 | 318719062236 |
| 12 | 9987013488640 |
| 13 | 340037795872369 |
| 14 | 12500401969233920 |
| 15 | 493467700789897408 |
| 16 | 20819865970795610112 |
| 17 | 934939160745193002321 |
| 18 | 44523294861684890664960 |