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 | 7 |
| 3 | 41 |
| 4 | 211 |
| 5 | 1009 |
| 6 | 4621 |
| 7 | 20593 |
| 8 | 90091 |
| 9 | 388961 |
| 10 | 1662805 |
| 11 | 7054321 |
| 12 | 29745717 |
| 13 | 124807201 |
| 14 | 521515801 |
| 15 | 2171645281 |
| 16 | 9016205851 |
| 17 | 37337699521 |
| 18 | 154277300101 |
| 19 | 636214748401 |
| 20 | 2619084047581 |
| 21 | 10765157488801 |
| 22 | 44186078238121 |
| 23 | 181135476007201 |
| 24 | 741694884711301 |