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 | 4 |
| 4 | 24 |
| 5 | 152 |
| 6 | 1056 |
| 7 | 7884 |
| 8 | 62336 |
| 9 | 516060 |
| 10 | 4435888 |
| 11 | 39338456 |
| 12 | 358164768 |
| 13 | 3335087752 |
| 14 | 31663393880 |
| 15 | 305740631660 |
| 16 | 2996450625216 |
| 17 | 29756512979124 |
| 18 | 298991371001192 |
| 19 | 3036071594865808 |
| 20 | 31123847225593944 |
| 21 | 321822051245586716 |
| 22 | 3353854189297573504 |
| 23 | 35203483037473883368 |
| 24 | 371948773494408980616 |
| 25 | 3953755503217954761364 |