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 | 2047 |
| 3 | 177146 |
| 4 | 4194303 |
| 5 | 48828124 |
| 6 | 362797055 |
| 7 | 1977326742 |
| 8 | 8589934591 |
| 9 | 31381059608 |
| 10 | 99999999999 |
| 11 | 285311670610 |
| 12 | 743008370687 |
| 13 | 1792160394036 |
| 14 | 4049565169663 |
| 15 | 8649755859374 |
| 16 | 17592186044415 |
| 17 | 34271896307632 |
| 18 | 64268410079231 |
| 19 | 116490258898218 |
| 20 | 204799999999999 |