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 | 4 |
| 3 | 14 |
| 4 | 52 |
| 5 | 248 |
| 6 | 1416 |
| 7 | 9172 |
| 8 | 66366 |
| 9 | 518868 |
| 10 | 4301350 |
| 11 | 37230364 |
| 12 | 333058463 |
| 13 | 3057319072 |
| 14 | 28656583950 |
| 15 | 273298352168 |
| 16 | 2645186193457 |
| 17 | 25931472185976 |
| 18 | 257086490694917 |
| 19 | 2574370590192556 |
| 20 | 26010904915620261 |