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 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 12 |
| 5 | 15 |
| 6 | 31 |
| 7 | 56 |
| 8 | 63 |
| 9 | 127 |
| 10 | 255 |
| 11 | 511 |
| 12 | 992 |
| 13 | 1023 |
| 14 | 2047 |
| 15 | 4095 |
| 16 | 8191 |
| 17 | 16256 |
| 18 | 16383 |
| 19 | 32767 |
| 20 | 65535 |
| 21 | 131071 |
| 22 | 262143 |
| 23 | 524287 |
| 24 | 1048575 |
| 25 | 2097151 |
| 26 | 4194303 |
| 27 | 8388607 |
| 28 | 16777215 |
| 29 | 33554431 |
| 30 | 67100672 |
| 31 | 67108863 |
| 32 | 134217727 |
| 33 | 268435455 |
| 34 | 536870911 |
| 35 | 1073741823 |
| 36 | 2147483647 |
| 37 | 4294967295 |
| 38 | 8589934591 |
| 39 | 17179738112 |
| 40 | 17179869183 |