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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 40 |
| 6 | 182 |
| 7 | 906 |
| 8 | 5404 |
| 9 | 35494 |
| 10 | 264178 |
| 11 | 2124078 |
| 12 | 18965372 |
| 13 | 181080940 |
| 14 | 1879988162 |
| 15 | 20764521072 |
| 16 | 246377199752 |
| 17 | 3085635516364 |
| 18 | 41182472709986 |
| 19 | 577129788232678 |
| 20 | 8552244962978250 |
| 21 | 132591961730782524 |
| 22 | 2161198867136837458 |