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 | 6 |
| 2 | 42 |
| 3 | 312 |
| 4 | 2394 |
| 5 | 18756 |
| 6 | 149136 |
| 7 | 1199232 |
| 8 | 9729882 |
| 9 | 79527084 |
| 10 | 654089292 |
| 11 | 5408896752 |
| 12 | 44941609584 |
| 13 | 375002110944 |
| 14 | 3141107339328 |
| 15 | 26402533581312 |
| 16 | 222635989516122 |
| 17 | 1882882811380284 |
| 18 | 15967419789558804 |
| 19 | 135752058036988848 |
| 20 | 1156869080242393644 |