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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 56 |
| 5 | 188 |
| 6 | 608 |
| 7 | 1920 |
| 8 | 5952 |
| 9 | 18192 |
| 10 | 54976 |
| 11 | 164608 |
| 12 | 489088 |
| 13 | 1443776 |
| 14 | 4238336 |
| 15 | 12382208 |
| 16 | 36022272 |
| 17 | 104407296 |
| 18 | 301618176 |
| 19 | 868765696 |
| 20 | 2495715328 |
| 21 | 7152286720 |
| 22 | 20452548608 |
| 23 | 58369409024 |
| 24 | 166276481024 |
| 25 | 472876388352 |