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 | 4 |
| 2 | 62 |
| 3 | 1440 |
| 4 | 30346 |
| 5 | 589556 |
| 6 | 10858046 |
| 7 | 192811016 |
| 8 | 3336192082 |
| 9 | 56642890908 |
| 10 | 948242161382 |
| 11 | 15706527467824 |
| 12 | 258068117928826 |
| 13 | 4214126476848580 |
| 14 | 68489478048350222 |
| 15 | 1109069751830483544 |
| 16 | 17909240724783047842 |
| 17 | 288575383662532867820 |
| 18 | 4642173797092097149238 |