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) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 39 |
| 6 | 129 |
| 7 | 411 |
| 8 | 1300 |
| 9 | 4065 |
| 10 | 12633 |
| 11 | 39046 |
| 12 | 120204 |
| 13 | 368844 |
| 14 | 1128837 |
| 15 | 3447303 |
| 16 | 10508592 |
| 17 | 31985085 |
| 18 | 97226733 |
| 19 | 295214316 |
| 20 | 895502520 |
| 21 | 2714106318 |
| 22 | 8219809425 |
| 23 | 24877611798 |
| 24 | 75248738292 |
| 25 | 227488953354 |
| 26 | 687408882709 |
| 27 | 2076269682831 |
| 28 | 6268788729240 |
| 29 | 18920387069731 |
| 30 | 57086882549253 |