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 | 5 |
| 2 | 26 |
| 3 | 140 |
| 4 | 776 |
| 5 | 4400 |
| 6 | 25376 |
| 7 | 148160 |
| 8 | 872576 |
| 9 | 5169920 |
| 10 | 30757376 |
| 11 | 183495680 |
| 12 | 1096779776 |
| 13 | 6563901440 |
| 14 | 39316299776 |
| 15 | 235629363200 |
| 16 | 1412702437376 |
| 17 | 8471919656960 |
| 18 | 50814338072576 |
| 19 | 304817308958720 |
| 20 | 1828628975845376 |