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 | 127 |
| 2 | 32767 |
| 3 | 8388607 |
| 4 | 2147483647 |
| 5 | 549755813887 |
| 6 | 140737488355327 |
| 7 | 36028797018963967 |
| 8 | 9223372036854775807 |
| 9 | 2361183241434822606847 |
| 10 | 604462909807314587353087 |
| 11 | 154742504910672534362390527 |
| 12 | 39614081257132168796771975167 |
| 13 | 10141204801825835211973625643007 |