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 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 3 |
| 5 | 9 |
| 6 | 23 |
| 7 | 73 |
| 8 | 229 |
| 9 | 796 |
| 10 | 2891 |
| 11 | 11118 |
| 12 | 44695 |
| 13 | 187825 |
| 14 | 820320 |
| 15 | 3716501 |
| 16 | 17413308 |
| 17 | 84209071 |
| 18 | 419461933 |
| 19 | 2148673503 |
| 20 | 11301526295 |
| 21 | 60956491070 |
| 22 | 336744177291 |
| 23 | 1903317319015 |
| 24 | 10995856040076 |
| 25 | 64873456288903 |
| 26 | 390544727861462 |
| 27 | 2397255454976268 |
| 28 | 14993279955728851 |