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) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | -7 |
| 3 | 69 |
| 4 | -715 |
| 5 | 8351 |
| 6 | -103735 |
| 7 | 1346247 |
| 8 | -18035023 |
| 9 | 247520970 |
| 10 | -3462344959 |
| 11 | 49181268701 |
| 12 | -707502644111 |
| 13 | 10286493363184 |
| 14 | -150913708053635 |
| 15 | 2231345941617611 |
| 16 | -33215679733509159 |
| 17 | 497392118745778015 |
| 18 | -7487512016559918595 |
| 19 | 113242852989349372915 |