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 | 2 |
| 2 | 10 |
| 3 | 60 |
| 4 | 397 |
| 5 | 2802 |
| 6 | 20710 |
| 7 | 158428 |
| 8 | 1244413 |
| 9 | 9980220 |
| 10 | 81394123 |
| 11 | 672998498 |
| 12 | 5628741195 |
| 13 | 47535483498 |
| 14 | 404790717079 |
| 15 | 3471892750622 |
| 16 | 29966295451511 |
| 17 | 260080708564964 |
| 18 | 2268416956569463 |
| 19 | 19872441881999354 |
| 20 | 174783803353387498 |