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 | -4 |
| 2 | 0 |
| 3 | 20 |
| 4 | 58 |
| 5 | 796 |
| 6 | 7858 |
| 7 | 40324 |
| 8 | 140194 |
| 9 | 2444744 |
| 10 | 40680494 |
| 11 | -7117319032 |
| 12 | -149539443124 |
| 13 | -223750776484 |
| 14 | -4960419494993024 |
| 15 | -46146161037854692 |
| 16 | -689434674121075448 |
| 17 | -132496988938839119444 |
| 18 | -9686633414582239854958 |
| 19 | -442788087926096759821484 |