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 | 32 |
| 3 | 162 |
| 4 | 800 |
| 5 | 3906 |
| 6 | 18992 |
| 7 | 92322 |
| 8 | 449600 |
| 9 | 2195586 |
| 10 | 10755152 |
| 11 | 52845282 |
| 12 | 260386400 |
| 13 | 1286217666 |
| 14 | 6367168112 |
| 15 | 31576971042 |
| 16 | 156839811200 |
| 17 | 779990182146 |
| 18 | 3883029321872 |
| 19 | 19347201973602 |
| 20 | 96463456484000 |
| 21 | 481224744361026 |