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 | 2 |
| 1 | 10 |
| 2 | 52 |
| 3 | 280 |
| 4 | 1552 |
| 5 | 8800 |
| 6 | 50752 |
| 7 | 296320 |
| 8 | 1745152 |
| 9 | 10339840 |
| 10 | 61514752 |
| 11 | 366991360 |
| 12 | 2193559552 |
| 13 | 13127802880 |
| 14 | 78632599552 |
| 15 | 471258726400 |
| 16 | 2825404874752 |
| 17 | 16943839313920 |
| 18 | 101628676145152 |
| 19 | 609634617917440 |