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) |
|---|---|
| 4 | 1 |
| 5 | 10 |
| 6 | 65 |
| 7 | 350 |
| 8 | 1700 |
| 9 | 7752 |
| 10 | 33915 |
| 11 | 144210 |
| 12 | 600875 |
| 13 | 2466750 |
| 14 | 10015005 |
| 15 | 40320150 |
| 16 | 161280600 |
| 17 | 641886000 |
| 18 | 2544619500 |
| 19 | 10056336264 |
| 20 | 39645171810 |
| 21 | 155989499540 |
| 22 | 612815891050 |
| 23 | 2404551645100 |
| 24 | 9425842448792 |
| 25 | 36921502679600 |
| 26 | 144539291740025 |
| 27 | 565588532895750 |
| 28 | 2212449261033375 |