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 | 4 |
| 2 | 18 |
| 3 | 48 |
| 4 | 180 |
| 5 | 432 |
| 6 | 1512 |
| 7 | 3456 |
| 8 | 11664 |
| 9 | 25920 |
| 10 | 85536 |
| 11 | 186624 |
| 12 | 606528 |
| 13 | 1306368 |
| 14 | 4199040 |
| 15 | 8957952 |
| 16 | 28553472 |
| 17 | 60466176 |
| 18 | 191476224 |
| 19 | 403107840 |
| 20 | 1269789696 |
| 21 | 2660511744 |
| 22 | 8344332288 |
| 23 | 17414258688 |
| 24 | 54419558400 |
| 25 | 113192681472 |
| 26 | 352638738432 |
| 27 | 731398864896 |
| 28 | 2272560758784 |