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 | 384 |
| 5 | 19100 |
| 6 | 557808 |
| 7 | 5841780 |
| 8 | 41338400 |
| 9 | 209264796 |
| 10 | 859752800 |
| 11 | 2982181004 |
| 12 | 9131392296 |
| 13 | 25196132260 |
| 14 | 63968987264 |
| 15 | 151223202900 |
| 16 | 336724832384 |
| 17 | 711538908572 |
| 18 | 1437022315440 |
| 19 | 2787781494732 |
| 20 | 5219454908200 |
| 21 | 9464698212228 |