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 | 12 |
| 4 | 256 |
| 5 | 1040 |
| 6 | 41472 |
| 7 | 407680 |
| 8 | 16515072 |
| 9 | 152845056 |
| 10 | 9897840000 |
| 11 | 89493288192 |
| 12 | 8732596764672 |
| 13 | 129785922489600 |
| 14 | 10576701872701440 |
| 15 | 210729768933600000 |
| 16 | 18446676793287966720 |
| 17 | 275746753962112254720 |
| 18 | 28084363369373740400640 |
| 19 | 791359800910482004224000 |