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 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 24 |
| 5 | 80 |
| 6 | 232 |
| 7 | 728 |
| 8 | 2160 |
| 9 | 6552 |
| 10 | 19600 |
| 11 | 59048 |
| 12 | 176880 |
| 13 | 531440 |
| 14 | 1593592 |
| 15 | 4782880 |
| 16 | 14346720 |
| 17 | 43046720 |
| 18 | 129133368 |
| 19 | 387420488 |
| 20 | 1162241760 |
| 21 | 3486783664 |
| 22 | 10460294152 |
| 23 | 31381059608 |
| 24 | 94142999520 |
| 25 | 282429536400 |
| 26 | 847288078000 |
| 27 | 2541865821768 |
| 28 | 7625595890640 |
| 29 | 22876792454960 |