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 | 11 |
| 2 | 31 |
| 3 | 71 |
| 4 | 151 |
| 5 | 311 |
| 6 | 631 |
| 7 | 2551 |
| 8 | 655351 |
| 9 | 2621431 |
| 10 | 10485751 |
| 11 | 5497558138871 |
| 12 | 10995116277751 |
| 13 | 175921860444151 |
| 14 | 737869762948382064631 |
| 15 | 396140812571321687967719751671 |