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) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 32 |
| 6 | 139 |
| 7 | 729 |
| 8 | 4515 |
| 9 | 32336 |
| 10 | 263205 |
| 11 | 2401183 |
| 12 | 24275037 |
| 13 | 269426592 |
| 14 | 3257394143 |
| 15 | 42615550453 |
| 16 | 599875100487 |
| 17 | 9040742057760 |
| 18 | 145251748024649 |
| 19 | 2478320458476795 |
| 20 | 44755020000606961 |
| 21 | 852823700470009056 |
| 22 | 17101229029400788083 |
| 23 | 359978633317886558801 |
| 24 | 7936631162022905081707 |