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 | 15 |
| 2 | 19 |
| 3 | 43 |
| 4 | 139 |
| 5 | 2059 |
| 6 | 8203 |
| 7 | 131083 |
| 8 | 524299 |
| 9 | 8388619 |
| 10 | 536870923 |
| 11 | 2147483659 |
| 12 | 137438953483 |
| 13 | 2199023255563 |
| 14 | 8796093022219 |
| 15 | 140737488355339 |
| 16 | 9007199254741003 |
| 17 | 576460752303423499 |
| 18 | 2305843009213693963 |
| 19 | 147573952589676412939 |
| 20 | 2361183241434822606859 |