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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 32 |
| 6 | 177 |
| 7 | 1142 |
| 8 | 8411 |
| 9 | 69692 |
| 10 | 642581 |
| 11 | 6534978 |
| 12 | 72754927 |
| 13 | 880877928 |
| 14 | 11530686953 |
| 15 | 162331760494 |
| 16 | 2446380427331 |
| 17 | 39300220067668 |
| 18 | 670480457586813 |
| 19 | 12106985274788506 |
| 20 | 230691361507912471 |
| 21 | 4625811718758963136 |