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 | 1 |
| 3 | 13 |
| 4 | 25 |
| 5 | 541 |
| 6 | 1561 |
| 7 | 47293 |
| 8 | 181945 |
| 9 | 7087261 |
| 10 | 34082521 |
| 11 | 1622632573 |
| 12 | 9363855865 |
| 13 | 526858348381 |
| 14 | 3547114323481 |
| 15 | 230283190977853 |
| 16 | 1771884893993785 |
| 17 | 130370767029135901 |
| 18 | 1128511554418948441 |
| 19 | 92801587319328411133 |
| 20 | 892562598748128067705 |
| 21 | 81124824998504073881821 |