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 | 2 |
| 4 | 9 |
| 5 | 54 |
| 6 | 374 |
| 7 | 2820 |
| 8 | 22485 |
| 9 | 186494 |
| 10 | 1592778 |
| 11 | 13914108 |
| 12 | 123750874 |
| 13 | 1116809628 |
| 14 | 10201516332 |
| 15 | 94140605832 |
| 16 | 876332565837 |
| 17 | 8219124900558 |
| 18 | 77594375595266 |
| 19 | 736785675010380 |
| 20 | 7031930543228910 |
| 21 | 67420537625021460 |
| 22 | 649070964647075700 |