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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 1 |
| 4 | 15 |
| 5 | 1 |
| 6 | 63 |
| 7 | 1 |
| 8 | 255 |
| 9 | 1 |
| 10 | 1023 |
| 11 | 1 |
| 12 | 4095 |
| 13 | 1 |
| 14 | 16383 |
| 15 | 1 |
| 16 | 65535 |
| 17 | 1 |
| 18 | 262143 |
| 19 | 1 |
| 20 | 1048575 |
| 21 | 1 |
| 22 | 4194303 |
| 23 | 1 |
| 24 | 16777215 |
| 25 | 1 |
| 26 | 67108863 |
| 27 | 1 |
| 28 | 268435455 |
| 29 | 1 |
| 30 | 1073741823 |
| 31 | 1 |
| 32 | 4294967295 |
| 33 | 1 |
| 34 | 17179869183 |
| 35 | 1 |
| 36 | 68719476735 |
| 37 | 1 |
| 38 | 274877906943 |
| 39 | 1 |
| 40 | 1099511627775 |
| 41 | 1 |