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 | 30 |
| 3 | 128 |
| 4 | 504 |
| 5 | 1872 |
| 6 | 6672 |
| 7 | 23040 |
| 8 | 77616 |
| 9 | 256288 |
| 10 | 832416 |
| 11 | 2666496 |
| 12 | 8441600 |
| 13 | 26454528 |
| 14 | 82174464 |
| 15 | 253280256 |
| 16 | 775316736 |
| 17 | 2358812160 |
| 18 | 7137023488 |
| 19 | 21487386624 |
| 20 | 64401106944 |
| 21 | 192229535744 |
| 22 | 571630694400 |
| 23 | 1693996941312 |
| 24 | 5004131659776 |
| 25 | 14738997288960 |
| 26 | 43293528760320 |