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 | 6 |
| 2 | 24 |
| 3 | 96 |
| 4 | 372 |
| 5 | 1416 |
| 6 | 5340 |
| 7 | 20040 |
| 8 | 75012 |
| 9 | 280392 |
| 10 | 1047324 |
| 11 | 3910440 |
| 12 | 14597508 |
| 13 | 54485736 |
| 14 | 203357724 |
| 15 | 758969736 |
| 16 | 2832570372 |
| 17 | 10571410056 |
| 18 | 39453266460 |
| 19 | 147242049000 |
| 20 | 549515715972 |
| 21 | 2050822387752 |
| 22 | 7653776980764 |
| 23 | 28564291826760 |
| 24 | 106603402909188 |
| 25 | 397849344975816 |
| 26 | 1484794027325724 |
| 27 | 5541326864990376 |