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 | -1 |
| 3 | -3 |
| 4 | 14 |
| 5 | 520 |
| 6 | 11185 |
| 7 | 239505 |
| 8 | 5510652 |
| 9 | 138456936 |
| 10 | 3803230815 |
| 11 | 113833152565 |
| 12 | 3695302326650 |
| 13 | 129479186068128 |
| 14 | 4874312730972685 |
| 15 | 196306448145080385 |
| 16 | 8425000059348756472 |
| 17 | 383956514250037779376 |
| 18 | 18521535576956405481147 |
| 19 | 942952190208348285876501 |