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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 106 |
| 6 | 549 |
| 7 | 3184 |
| 8 | 20353 |
| 9 | 141615 |
| 10 | 1063399 |
| 11 | 8554800 |
| 12 | 73281988 |
| 13 | 665141182 |
| 14 | 6369920854 |
| 15 | 64133095134 |
| 16 | 676690490875 |
| 17 | 7462023572238 |
| 18 | 85786458777923 |
| 19 | 1025956348473929 |
| 20 | 12739037494941490 |