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 | 7 |
| 3 | 60 |
| 4 | 579 |
| 5 | 6017 |
| 6 | 65732 |
| 7 | 744264 |
| 8 | 8656795 |
| 9 | 102819507 |
| 10 | 1241838271 |
| 11 | 15205587136 |
| 12 | 188320591092 |
| 13 | 2354971302700 |
| 14 | 29693879866840 |
| 15 | 377104836064720 |
| 16 | 4819271465838795 |
| 17 | 61930407776801015 |
| 18 | 799765007716515125 |
| 19 | 10373651783800459340 |
| 20 | 135089139660222638795 |