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 | 6 |
| 4 | 23 |
| 5 | 107 |
| 6 | 585 |
| 7 | 3669 |
| 8 | 25932 |
| 9 | 203768 |
| 10 | 1761109 |
| 11 | 16595757 |
| 12 | 169287873 |
| 13 | 1857903529 |
| 14 | 21823488238 |
| 15 | 273130320026 |
| 16 | 3627845694283 |
| 17 | 50962676849199 |
| 18 | 754814462534449 |
| 19 | 11754778469338581 |
| 20 | 191998054346198680 |