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 | 11 |
| 3 | 31 |
| 4 | 71 |
| 5 | 151 |
| 6 | 311 |
| 7 | 631 |
| 8 | 1271 |
| 9 | 2551 |
| 10 | 5111 |
| 11 | 10231 |
| 12 | 20471 |
| 13 | 40951 |
| 14 | 81911 |
| 15 | 163831 |
| 16 | 327671 |
| 17 | 655351 |
| 18 | 1310711 |
| 19 | 2621431 |
| 20 | 5242871 |
| 21 | 10485751 |
| 22 | 20971511 |
| 23 | 41943031 |
| 24 | 83886071 |
| 25 | 167772151 |
| 26 | 335544311 |
| 27 | 671088631 |
| 28 | 1342177271 |
| 29 | 2684354551 |