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 | 4 |
| 4 | 18 |
| 5 | 74 |
| 6 | 311 |
| 7 | 1296 |
| 8 | 5432 |
| 9 | 22796 |
| 10 | 95958 |
| 11 | 404812 |
| 12 | 1711600 |
| 13 | 7250970 |
| 14 | 30772989 |
| 15 | 130810512 |
| 16 | 556867224 |
| 17 | 2373764416 |
| 18 | 10130935783 |
| 19 | 43285462884 |
| 20 | 185129287262 |
| 21 | 792525473552 |
| 22 | 3395664830670 |
| 23 | 14560682746632 |
| 24 | 62482560679368 |
| 25 | 268307898599664 |
| 26 | 1152883194581155 |
| 27 | 4956738399534376 |
| 28 | 21323028570642414 |
| 29 | 91775945084805898 |