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 | -7 |
| 2 | -3 |
| 3 | 21 |
| 4 | 117 |
| 5 | 2037 |
| 6 | 8181 |
| 7 | 131061 |
| 8 | 524277 |
| 9 | 8388597 |
| 10 | 536870901 |
| 11 | 2147483637 |
| 12 | 137438953461 |
| 13 | 2199023255541 |
| 14 | 8796093022197 |
| 15 | 140737488355317 |
| 16 | 9007199254740981 |
| 17 | 576460752303423477 |
| 18 | 2305843009213693941 |
| 19 | 147573952589676412917 |
| 20 | 2361183241434822606837 |