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 | 3 |
| 2 | 9 |
| 3 | 20 |
| 4 | 54 |
| 5 | 112 |
| 6 | 240 |
| 7 | 648 |
| 8 | 1344 |
| 9 | 2816 |
| 10 | 5760 |
| 11 | 12800 |
| 12 | 26624 |
| 13 | 62208 |
| 14 | 129024 |
| 15 | 270336 |
| 16 | 552960 |
| 17 | 1114112 |
| 18 | 2293760 |
| 19 | 4915200 |
| 20 | 9961472 |
| 21 | 20447232 |
| 22 | 47775744 |
| 23 | 96468992 |
| 24 | 198180864 |
| 25 | 411041792 |
| 26 | 830472192 |
| 27 | 1698693120 |
| 28 | 3422552064 |
| 29 | 7046430720 |