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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 6 |
| 6 | 150 |
| 7 | 400 |
| 8 | 4080 |
| 9 | 15480 |
| 10 | 127812 |
| 11 | 269340 |
| 12 | 3493530 |
| 13 | 5777190 |
| 14 | 57262050 |
| 15 | 210945176 |
| 16 | 1030384035 |
| 17 | 2493913170 |
| 18 | 32176432430 |
| 19 | 51785999300 |
| 20 | 562228198086 |
| 21 | 1805427491520 |
| 22 | 10438821574410 |
| 23 | 22865672706000 |