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) |
|---|---|
| 4 | 5 |
| 5 | 11 |
| 6 | 27 |
| 7 | 71 |
| 8 | 201 |
| 9 | 603 |
| 10 | 1905 |
| 11 | 6318 |
| 12 | 21888 |
| 13 | 78912 |
| 14 | 295260 |
| 15 | 1143536 |
| 16 | 4574144 |
| 17 | 18859680 |
| 18 | 80014848 |
| 19 | 348776640 |
| 20 | 1559776320 |
| 21 | 7147792848 |
| 22 | 33526120320 |
| 23 | 160785625902 |
| 24 | 787685472000 |
| 25 | 3938427360000 |
| 26 | 20082117976800 |
| 27 | 104349745817240 |
| 28 | 552166953609600 |
| 29 | 2973510046027938 |