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 | 8 |
| 3 | 168 |
| 4 | 714 |
| 5 | 1870 |
| 6 | 7920 |
| 7 | 54288 |
| 8 | 229970 |
| 9 | 602070 |
| 10 | 2550408 |
| 11 | 10803704 |
| 12 | 28284465 |
| 13 | 74049690 |
| 14 | 193864606 |
| 15 | 821223648 |
| 16 | 3478759200 |
| 17 | 9107509825 |
| 18 | 23843770274 |
| 19 | 62423800998 |
| 20 | 264431464440 |
| 21 | 1120149658760 |
| 22 | 2932589879121 |
| 23 | 7677619978602 |