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 | 0 |
| 1 | 4 |
| 2 | 48 |
| 3 | 448 |
| 4 | 3840 |
| 5 | 31744 |
| 6 | 258048 |
| 7 | 2080768 |
| 8 | 16711680 |
| 9 | 133955584 |
| 10 | 1072693248 |
| 11 | 8585740288 |
| 12 | 68702699520 |
| 13 | 549688705024 |
| 14 | 4397778075648 |
| 15 | 35183298347008 |
| 16 | 281470681743360 |
| 17 | 2251782633816064 |
| 18 | 18014329790005248 |
| 19 | 144114913197948928 |
| 20 | 1152920405095219200 |