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 | 1 |
| 2 | -2 |
| 3 | 9 |
| 4 | -65 |
| 5 | 653 |
| 6 | -8432 |
| 7 | 133190 |
| 8 | -2488589 |
| 9 | 53690330 |
| 10 | -1313508417 |
| 11 | 35929413073 |
| 12 | -1086587503799 |
| 13 | 35998774583176 |
| 14 | -1296581783771904 |
| 15 | 50442455219483951 |
| 16 | -2108020240791081088 |
| 17 | 94179374365406507609 |
| 18 | -4479409651990684350045 |
| 19 | 225977974437623955594777 |