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 | 5 |
| 2 | 24 |
| 3 | 116 |
| 4 | 560 |
| 5 | 2704 |
| 6 | 13056 |
| 7 | 63040 |
| 8 | 304384 |
| 9 | 1469696 |
| 10 | 7096320 |
| 11 | 34264064 |
| 12 | 165441536 |
| 13 | 798822400 |
| 14 | 3857055744 |
| 15 | 18623512576 |
| 16 | 89922273280 |
| 17 | 434183143424 |
| 18 | 2096421666816 |
| 19 | 10122419240960 |
| 20 | 48875363631104 |
| 21 | 235991131488256 |
| 22 | 1139465980477440 |
| 23 | 5501828447862784 |