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 | 3 |
| 2 | 9 |
| 3 | 31 |
| 4 | 141 |
| 5 | 831 |
| 6 | 5773 |
| 7 | 45459 |
| 8 | 403161 |
| 9 | 3990331 |
| 10 | 43544721 |
| 11 | 518940423 |
| 12 | 6706062949 |
| 13 | 93404895351 |
| 14 | 1394851282581 |
| 15 | 22230473112571 |
| 16 | 376610264357553 |
| 17 | 6758060929028979 |
| 18 | 128047472471583001 |
| 19 | 2554547113522500591 |
| 20 | 53523844242070603581 |
| 21 | 1175091669834676927663 |