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 | 3 |
| 2 | 9 |
| 3 | 30 |
| 4 | 108 |
| 5 | 408 |
| 6 | 1584 |
| 7 | 6240 |
| 8 | 24768 |
| 9 | 98688 |
| 10 | 393984 |
| 11 | 1574400 |
| 12 | 6294528 |
| 13 | 25171968 |
| 14 | 100675584 |
| 15 | 402677760 |
| 16 | 1610661888 |
| 17 | 6442549248 |
| 18 | 25770000384 |
| 19 | 103079608320 |
| 20 | 412317646848 |
| 21 | 1649269014528 |
| 22 | 6597072912384 |
| 23 | 26388285358080 |
| 24 | 105553128849408 |