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 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 18 |
| 7 | 54 |
| 8 | 173 |
| 9 | 605 |
| 10 | 2274 |
| 11 | 9020 |
| 12 | 37486 |
| 13 | 163128 |
| 14 | 743101 |
| 15 | 3535765 |
| 16 | 17518018 |
| 17 | 90126158 |
| 18 | 480514430 |
| 19 | 2650912738 |
| 20 | 15112253425 |
| 21 | 88903779401 |
| 22 | 539003066674 |
| 23 | 3363608949132 |
| 24 | 21581457167994 |
| 25 | 142227480847092 |
| 26 | 961868098767105 |
| 27 | 6669657795455817 |
| 28 | 47380035801732034 |
| 29 | 344555811578909254 |
| 30 | 2563218995058696890 |