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 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 27 |
| 6 | 177 |
| 7 | 1137 |
| 8 | 7962 |
| 9 | 62730 |
| 10 | 555894 |
| 11 | 5487894 |
| 12 | 59740389 |
| 13 | 710770989 |
| 14 | 9174169647 |
| 15 | 127661751951 |
| 16 | 1904975487876 |
| 17 | 30341995264356 |
| 18 | 513771331466556 |
| 19 | 9215499383108604 |
| 20 | 174548332364310423 |
| 21 | 3481204991988350223 |
| 22 | 72920994844093190013 |
| 23 | 1600596371590399670013 |