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) |
|---|---|
| 4 | 1 |
| 5 | 10 |
| 6 | 118 |
| 7 | 1656 |
| 8 | 27326 |
| 9 | 520626 |
| 10 | 11271436 |
| 11 | 273613032 |
| 12 | 7365210840 |
| 13 | 217823497200 |
| 14 | 7022714928604 |
| 15 | 245186433880584 |
| 16 | 9217032342988575 |
| 17 | 371216529334562246 |
| 18 | 15948164256621353088 |
| 19 | 728062466187371268960 |
| 20 | 35197679178007576031784 |