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) |
|---|---|
| 0 | 3 |
| 1 | 5 |
| 2 | 12 |
| 3 | 33 |
| 4 | 98 |
| 5 | 306 |
| 6 | 990 |
| 7 | 3289 |
| 8 | 11154 |
| 9 | 38454 |
| 10 | 134368 |
| 11 | 474810 |
| 12 | 1693812 |
| 13 | 6091780 |
| 14 | 22064130 |
| 15 | 80410185 |
| 16 | 294647250 |
| 17 | 1084922190 |
| 18 | 4012165080 |
| 19 | 14895504030 |
| 20 | 55496654460 |
| 21 | 207431394300 |
| 22 | 777601790940 |
| 23 | 2922867908298 |
| 24 | 11013796950228 |
| 25 | 41596652545756 |
| 26 | 157434454904160 |
| 27 | 597029454416724 |
| 28 | 2268232385053096 |