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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 14 |
| 5 | 52 |
| 6 | 204 |
| 7 | 840 |
| 8 | 3574 |
| 9 | 15588 |
| 10 | 69332 |
| 11 | 313272 |
| 12 | 1433964 |
| 13 | 6635400 |
| 14 | 30988312 |
| 15 | 145871248 |
| 16 | 691403686 |
| 17 | 3296979524 |
| 18 | 15805913476 |
| 19 | 76135613784 |
| 20 | 368304184900 |
| 21 | 1788518253080 |
| 22 | 8715477003688 |
| 23 | 42605364060656 |
| 24 | 208878870197436 |
| 25 | 1026781984000680 |
| 26 | 5059692979338824 |
| 27 | 24989145569112880 |
| 28 | 123676728224877464 |
| 29 | 613295203581498768 |
| 30 | 3046761116509464624 |