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 | 2 |
| 2 | 30 |
| 3 | 420 |
| 4 | 5852 |
| 5 | 81510 |
| 6 | 1135290 |
| 7 | 15812552 |
| 8 | 220240440 |
| 9 | 3067553610 |
| 10 | 42725510102 |
| 11 | 595089587820 |
| 12 | 8288528719380 |
| 13 | 115444312483502 |
| 14 | 1607931846049650 |
| 15 | 22395601532211600 |
| 16 | 311930489604912752 |
| 17 | 4344631252936566930 |
| 18 | 60512907051507024270 |
| 19 | 842836067468161772852 |