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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 256 |
| 6 | 7255 |
| 7 | 149660 |
| 8 | 2681063 |
| 9 | 44659776 |
| 10 | 714287535 |
| 11 | 11154475420 |
| 12 | 171673613023 |
| 13 | 2618246526896 |
| 14 | 39701554817015 |
| 15 | 599773397512380 |
| 16 | 9038881598035383 |
| 17 | 136004367641775616 |
| 18 | 2044264589908169695 |
| 19 | 30705868769902628540 |
| 20 | 461006369270166660143 |
| 21 | 6919274132365824549936 |