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) |
|---|---|
| 1 | 6 |
| 2 | 48 |
| 3 | 380 |
| 4 | 2860 |
| 5 | 19896 |
| 6 | 129648 |
| 7 | 810964 |
| 8 | 4962056 |
| 9 | 30034672 |
| 10 | 180893724 |
| 11 | 1087112084 |
| 12 | 6527090276 |
| 13 | 39173693352 |
| 14 | 235070531992 |
| 15 | 1410496377492 |
| 16 | 8463170413616 |
| 17 | 50779536937024 |
| 18 | 304678626418660 |
| 19 | 1828075665965204 |
| 20 | 10968465043204908 |