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 | 6 |
| 3 | 26 |
| 4 | 146 |
| 5 | 1014 |
| 6 | 8374 |
| 7 | 80282 |
| 8 | 875874 |
| 9 | 10719734 |
| 10 | 145422182 |
| 11 | 2166117018 |
| 12 | 35143677106 |
| 13 | 616926078326 |
| 14 | 11650276119702 |
| 15 | 235510563023642 |
| 16 | 5074238094097538 |
| 17 | 116081921186069622 |
| 18 | 2810093148179120710 |
| 19 | 71767508789469271322 |
| 20 | 1928439105298059705042 |