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 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 70 |
| 6 | 464 |
| 7 | 3482 |
| 8 | 27779 |
| 9 | 233556 |
| 10 | 2038484 |
| 11 | 18357672 |
| 12 | 169599492 |
| 13 | 1601270562 |
| 14 | 15401735750 |
| 15 | 150547249932 |
| 16 | 1492451793728 |
| 17 | 14980801247673 |
| 18 | 152047178479946 |
| 19 | 1558569469867824 |
| 20 | 16119428039548246 |