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 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 24 |
| 5 | 78 |
| 6 | 317 |
| 7 | 1636 |
| 8 | 10752 |
| 9 | 89871 |
| 10 | 955536 |
| 11 | 12930172 |
| 12 | 222618065 |
| 13 | 4874855542 |
| 14 | 135781292308 |
| 15 | 4811103270053 |
| 16 | 216847500834512 |
| 17 | 12432143862756778 |
| 18 | 906625645142897789 |
| 19 | 84102571511631809864 |
| 20 | 9923979699312024569440 |
| 21 | 1489546408205976627946331 |