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 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 23 |
| 5 | 115 |
| 6 | 697 |
| 7 | 4925 |
| 8 | 39623 |
| 9 | 357955 |
| 10 | 3589177 |
| 11 | 39558845 |
| 12 | 475412423 |
| 13 | 6187461955 |
| 14 | 86702878777 |
| 15 | 1301486906045 |
| 16 | 20836087009223 |
| 17 | 354385941189955 |
| 18 | 6381537618718777 |
| 19 | 121290714467642045 |
| 20 | 2426520470557921223 |
| 21 | 50969651457241797955 |
| 22 | 1121574207307049758777 |