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 | 0 |
| 2 | 0 |
| 3 | 35 |
| 4 | 70 |
| 5 | 1008 |
| 6 | 7560 |
| 7 | 75570 |
| 8 | 804375 |
| 9 | 9443720 |
| 10 | 120408288 |
| 11 | 1658028645 |
| 12 | 24515212540 |
| 13 | 387332966720 |
| 14 | 6511826843280 |
| 15 | 116059273664436 |
| 16 | 2185693176650685 |
| 17 | 43366955622595920 |
| 18 | 904164368153680480 |