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 | 15 |
| 4 | 75 |
| 5 | 381 |
| 6 | 1947 |
| 7 | 9975 |
| 8 | 51159 |
| 9 | 262497 |
| 10 | 1347123 |
| 11 | 6913911 |
| 12 | 35485779 |
| 13 | 182133885 |
| 14 | 934823451 |
| 15 | 4798101855 |
| 16 | 24626900271 |
| 17 | 126400914849 |
| 18 | 648769995939 |
| 19 | 3329901037119 |
| 20 | 17091174551835 |
| 21 | 87722802540957 |
| 22 | 450249343708827 |
| 23 | 2310966659437671 |
| 24 | 11861354115061383 |