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 | 21 |
| 4 | 69 |
| 5 | 266 |
| 6 | 1574 |
| 7 | 13504 |
| 8 | 93906 |
| 9 | 551477 |
| 10 | 3159693 |
| 11 | 18792129 |
| 12 | 113862870 |
| 13 | 692747205 |
| 14 | 4226551294 |
| 15 | 25828653795 |
| 16 | 157805371000 |
| 17 | 963306137176 |
| 18 | 5876339680839 |
| 19 | 35834865220658 |
| 20 | 218515617055715 |
| 21 | 1332575380148292 |