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 | 4 |
| 2 | 24 |
| 3 | 192 |
| 4 | 1792 |
| 5 | 18240 |
| 6 | 196224 |
| 7 | 2194176 |
| 8 | 25247232 |
| 9 | 296979456 |
| 10 | 3555010560 |
| 11 | 43165900800 |
| 12 | 530362220544 |
| 13 | 6581594275840 |
| 14 | 82373440339968 |
| 15 | 1038579580796928 |
| 16 | 13179023462498304 |
| 17 | 168183976239562752 |
| 18 | 2157085003249876992 |
| 19 | 27790652486543474688 |
| 20 | 359485965093121818624 |