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 | 2 |
| 3 | 8 |
| 4 | 30 |
| 5 | 124 |
| 6 | 516 |
| 7 | 2232 |
| 8 | 9750 |
| 9 | 43400 |
| 10 | 195248 |
| 11 | 887784 |
| 12 | 4068740 |
| 13 | 18780048 |
| 14 | 87191964 |
| 15 | 406900992 |
| 16 | 1907343750 |
| 17 | 8975758272 |
| 18 | 42385503300 |
| 19 | 200773540296 |
| 20 | 953674218720 |
| 21 | 4541306267856 |
| 22 | 21674415838068 |
| 23 | 103660251783288 |