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 | 6 |
| 4 | 33 |
| 5 | 170 |
| 6 | 861 |
| 7 | 4326 |
| 8 | 21673 |
| 9 | 108450 |
| 10 | 542421 |
| 11 | 2712446 |
| 12 | 13562913 |
| 13 | 67815930 |
| 14 | 339082381 |
| 15 | 1695417366 |
| 16 | 8477097753 |
| 17 | 42385510610 |
| 18 | 211927596741 |
| 19 | 1059638071086 |
| 20 | 5298190530193 |
| 21 | 26490953000490 |
| 22 | 132454765701501 |
| 23 | 662273829905606 |