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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 82 |
| 5 | 495 |
| 6 | 3144 |
| 7 | 20874 |
| 8 | 142766 |
| 9 | 1000083 |
| 10 | 7136463 |
| 11 | 51699614 |
| 12 | 379214625 |
| 13 | 2810720045 |
| 14 | 21018835670 |
| 15 | 158389275075 |
| 16 | 1201541422730 |
| 17 | 9168456492986 |
| 18 | 70324572634341 |
| 19 | 541910543713685 |
| 20 | 4193257236992896 |
| 21 | 32568879336517050 |
| 22 | 253822497160605899 |
| 23 | 1984276479881989537 |
| 24 | 15556238037968354214 |
| 25 | 122274773948426045945 |