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) |
|---|---|
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 32 |
| 6 | 120 |
| 7 | 580 |
| 8 | 3392 |
| 9 | 23244 |
| 10 | 182776 |
| 11 | 1622468 |
| 12 | 16045200 |
| 13 | 174894172 |
| 14 | 2082824744 |
| 15 | 26902998516 |
| 16 | 374570250688 |
| 17 | 5591767768460 |
| 18 | 89095070783832 |
| 19 | 1509041577895204 |
| 20 | 27073887615758576 |
| 21 | 512898265609845948 |
| 22 | 10230945527263709320 |
| 23 | 214337863242231108692 |