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 | 0 |
| 2 | 30 |
| 3 | 130 |
| 4 | 900 |
| 5 | 5368 |
| 6 | 33380 |
| 7 | 205080 |
| 8 | 1264378 |
| 9 | 7787228 |
| 10 | 47975704 |
| 11 | 295543282 |
| 12 | 1820672982 |
| 13 | 11216042008 |
| 14 | 69095255496 |
| 15 | 425653839018 |
| 16 | 2622194869596 |
| 17 | 16153749662332 |
| 18 | 99513440156936 |
| 19 | 613041859314376 |
| 20 | 3776578532115986 |