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 | 5 |
| 4 | 24 |
| 5 | 120 |
| 6 | 956 |
| 7 | 13214 |
| 8 | 275848 |
| 9 | 10613479 |
| 10 | 601955190 |
| 11 | 63788179593 |
| 12 | 9985272721908 |
| 13 | 2906903866536978 |
| 14 | 1268802939666164781 |
| 15 | 1023198355173637429689 |
| 16 | 1258181815243248217067175 |
| 17 | 2834890911778762731361375215 |
| 18 | 9900896274205100008273760895560 |