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 | 2 |
| 2 | 8 |
| 3 | 56 |
| 4 | 448 |
| 5 | 3920 |
| 6 | 36288 |
| 7 | 349440 |
| 8 | 3464448 |
| 9 | 35125760 |
| 10 | 362522624 |
| 11 | 3795914240 |
| 12 | 40224968704 |
| 13 | 430579701760 |
| 14 | 4648899846144 |
| 15 | 50568103690240 |
| 16 | 553632271155200 |
| 17 | 6096025799852032 |
| 18 | 67464070696927232 |
| 19 | 750003531943903232 |
| 20 | 8371814935842258944 |