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 | 2 |
| 3 | 11 |
| 4 | 38 |
| 5 | 257 |
| 6 | 1040 |
| 7 | 7646 |
| 8 | 33374 |
| 9 | 256718 |
| 10 | 1171454 |
| 11 | 9270560 |
| 12 | 43558064 |
| 13 | 351490167 |
| 14 | 1686018600 |
| 15 | 13799914556 |
| 16 | 67223728270 |
| 17 | 556203232266 |
| 18 | 2741975026412 |
| 19 | 22880729474777 |
| 20 | 113875773363274 |
| 21 | 956800135969601 |