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 | 3 |
| 3 | 18 |
| 4 | 112 |
| 5 | 755 |
| 6 | 5348 |
| 7 | 39302 |
| 8 | 296916 |
| 9 | 2291861 |
| 10 | 17997052 |
| 11 | 143319918 |
| 12 | 1154728056 |
| 13 | 9395809374 |
| 14 | 77099733884 |
| 15 | 637298480966 |
| 16 | 5301568498768 |
| 17 | 44351526986704 |
| 18 | 372890978840156 |
| 19 | 3149155955471690 |
| 20 | 26702387443603200 |
| 21 | 227238745573918511 |
| 22 | 1940201017862028108 |