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 | 1 |
| 3 | 7 |
| 4 | 29 |
| 5 | 121 |
| 6 | 649 |
| 7 | 5041 |
| 8 | 42909 |
| 9 | 364561 |
| 10 | 3515651 |
| 11 | 39916801 |
| 12 | 486821873 |
| 13 | 6227020801 |
| 14 | 86497214231 |
| 15 | 1307843292757 |
| 16 | 21004582611869 |
| 17 | 355687428096001 |
| 18 | 6390006277567483 |
| 19 | 121645100408832001 |
| 20 | 2435277595236694779 |
| 21 | 51091124681475552961 |
| 22 | 1123451899297248225431 |