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) |
|---|---|
| 2 | 0 |
| 3 | 2 |
| 4 | 6 |
| 5 | 18 |
| 6 | 52 |
| 7 | 146 |
| 8 | 406 |
| 9 | 1126 |
| 10 | 3124 |
| 11 | 8684 |
| 12 | 24202 |
| 13 | 67640 |
| 14 | 189576 |
| 15 | 532786 |
| 16 | 1501254 |
| 17 | 4240550 |
| 18 | 12005780 |
| 19 | 34063896 |
| 20 | 96844082 |
| 21 | 275848044 |
| 22 | 787104288 |
| 23 | 2249633916 |
| 24 | 6439678858 |
| 25 | 18460717684 |
| 26 | 52994100984 |
| 27 | 152323413890 |
| 28 | 438363476086 |