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 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 24 |
| 6 | 115 |
| 7 | 662 |
| 8 | 4456 |
| 9 | 34323 |
| 10 | 298220 |
| 11 | 2885156 |
| 12 | 30760556 |
| 13 | 358379076 |
| 14 | 4530375092 |
| 15 | 61762729722 |
| 16 | 903311893770 |
| 17 | 14108704577103 |
| 18 | 234387946711329 |
| 19 | 4127027097703638 |
| 20 | 76774080851679152 |
| 21 | 1504640319524566870 |
| 22 | 30986929089570280955 |
| 23 | 669023741837953551188 |