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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 24 |
| 6 | 131 |
| 7 | 843 |
| 8 | 6275 |
| 9 | 52988 |
| 10 | 500442 |
| 11 | 5226842 |
| 12 | 59818300 |
| 13 | 744405515 |
| 14 | 10008118595 |
| 15 | 144561713037 |
| 16 | 2232675345794 |
| 17 | 36715105686391 |
| 18 | 640474621418148 |
| 19 | 11813198572823623 |
| 20 | 229701083360459334 |
| 21 | 4696111037591613052 |