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 | 3 |
| 2 | 15 |
| 3 | 54 |
| 4 | 175 |
| 5 | 543 |
| 6 | 1642 |
| 7 | 4875 |
| 8 | 14271 |
| 9 | 41310 |
| 10 | 118487 |
| 11 | 337263 |
| 12 | 953810 |
| 13 | 2682579 |
| 14 | 7508655 |
| 15 | 20929158 |
| 16 | 58121407 |
| 17 | 160877055 |
| 18 | 443993146 |
| 19 | 1222110555 |
| 20 | 3355879647 |
| 21 | 9195143598 |
| 22 | 25144855655 |
| 23 | 68635721679 |
| 24 | 187035899810 |
| 25 | 508896450723 |
| 26 | 1382653280847 |
| 27 | 3751638404310 |