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 | 4 |
| 2 | 15 |
| 3 | 84 |
| 4 | 715 |
| 5 | 8568 |
| 6 | 134596 |
| 7 | 2629575 |
| 8 | 61523748 |
| 9 | 1677106640 |
| 10 | 52179482355 |
| 11 | 1823810410032 |
| 12 | 70724320184700 |
| 13 | 3012192716517082 |
| 14 | 139737927523546800 |
| 15 | 7012067478708989884 |
| 16 | 378371310857796292200 |
| 17 | 21843987843214746108900 |