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 | 5 |
| 2 | 30 |
| 3 | 198 |
| 4 | 1386 |
| 5 | 10098 |
| 6 | 75735 |
| 7 | 580635 |
| 8 | 4528953 |
| 9 | 35819901 |
| 10 | 286559208 |
| 11 | 2314516680 |
| 12 | 18846778680 |
| 13 | 154543585176 |
| 14 | 1274984577702 |
| 15 | 10574872085646 |
| 16 | 88123934047050 |
| 17 | 737458184920050 |
| 18 | 6194648753328420 |
| 19 | 52212039492339540 |
| 20 | 441429061162507020 |
| 21 | 3742550735942994300 |