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) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 30 |
| 5 | 150 |
| 6 | 870 |
| 7 | 5910 |
| 8 | 46230 |
| 9 | 409110 |
| 10 | 4037910 |
| 11 | 43954710 |
| 12 | 522956310 |
| 13 | 6749977110 |
| 14 | 93928268310 |
| 15 | 1401602636310 |
| 16 | 22324392524310 |
| 17 | 378011820620310 |
| 18 | 6780385526348310 |