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 | 9 |
| 5 | 46 |
| 6 | 262 |
| 7 | 1588 |
| 8 | 10053 |
| 9 | 65686 |
| 10 | 439658 |
| 11 | 2999116 |
| 12 | 20774154 |
| 13 | 145726348 |
| 14 | 1033125004 |
| 15 | 7390626280 |
| 16 | 53281906861 |
| 17 | 386732675046 |
| 18 | 2823690230850 |
| 19 | 20725376703324 |
| 20 | 152833785130398 |
| 21 | 1131770853856100 |
| 22 | 8412813651862868 |