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 | 3 |
| 3 | 19 |
| 4 | 47 |
| 5 | 601 |
| 6 | 2039 |
| 7 | 35281 |
| 8 | -26881 |
| 9 | 4898881 |
| 10 | -8104321 |
| 11 | 439084801 |
| 12 | 576132479 |
| 13 | 80951270401 |
| 14 | -913158005761 |
| 15 | 49506372115201 |
| 16 | -558073906790401 |
| 17 | 6046686277632001 |
| 18 | 79958674981785599 |
| 19 | 2311256907767808001 |
| 20 | -115583806104986419201 |