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) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 40 |
| 5 | 108 |
| 6 | 224 |
| 7 | 480 |
| 8 | 1296 |
| 9 | 2688 |
| 10 | 5632 |
| 11 | 11520 |
| 12 | 25600 |
| 13 | 53248 |
| 14 | 124416 |
| 15 | 258048 |
| 16 | 540672 |
| 17 | 1105920 |
| 18 | 2228224 |
| 19 | 4587520 |
| 20 | 9830400 |
| 21 | 19922944 |
| 22 | 40894464 |
| 23 | 95551488 |
| 24 | 192937984 |
| 25 | 396361728 |
| 26 | 822083584 |
| 27 | 1660944384 |
| 28 | 3397386240 |
| 29 | 6845104128 |