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 | 1 |
| 3 | 5 |
| 4 | 24 |
| 5 | 139 |
| 6 | 945 |
| 7 | 7377 |
| 8 | 65016 |
| 9 | 638418 |
| 10 | 6910650 |
| 11 | 81747665 |
| 12 | 1049089470 |
| 13 | 14516096009 |
| 14 | 215419836359 |
| 15 | 3412889885571 |
| 16 | 57492203734320 |
| 17 | 1026121982213480 |
| 18 | 19342642266760680 |
| 19 | 383995631680561234 |
| 20 | 8007915240045479980 |
| 21 | 175020604366224762038 |
| 22 | 4000551483475536398178 |