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 | 0 |
| 2 | 3 |
| 3 | 6 |
| 4 | 15 |
| 5 | 28 |
| 6 | 61 |
| 7 | 126 |
| 8 | 251 |
| 9 | 504 |
| 10 | 1017 |
| 11 | 2042 |
| 12 | 4095 |
| 13 | 8180 |
| 14 | 16373 |
| 15 | 32758 |
| 16 | 65523 |
| 17 | 131056 |
| 18 | 262129 |
| 19 | 524274 |
| 20 | 1048567 |
| 21 | 2097148 |
| 22 | 4194285 |
| 23 | 8388590 |
| 24 | 16777195 |
| 25 | 33554408 |
| 26 | 67108841 |
| 27 | 134217706 |
| 28 | 268435439 |
| 29 | 536870884 |
| 30 | 1073741797 |
| 31 | 2147483622 |