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 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 176 |
| 5 | 1376 |
| 6 | 10944 |
| 7 | 87424 |
| 8 | 699136 |
| 9 | 5592576 |
| 10 | 44739584 |
| 11 | 357914624 |
| 12 | 2863312896 |
| 13 | 22906494976 |
| 14 | 183251943424 |
| 15 | 1466015514624 |
| 16 | 11728124051456 |
| 17 | 93824992280576 |
| 18 | 750599937982464 |
| 19 | 6004799503335424 |
| 20 | 48038396025634816 |