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 | 1 |
| 1 | 3 |
| 2 | 11 |
| 3 | 39 |
| 4 | 131 |
| 5 | 423 |
| 6 | 1331 |
| 7 | 4119 |
| 8 | 12611 |
| 9 | 38343 |
| 10 | 116051 |
| 11 | 350199 |
| 12 | 1054691 |
| 13 | 3172263 |
| 14 | 9533171 |
| 15 | 28632279 |
| 16 | 85962371 |
| 17 | 258018183 |
| 18 | 774316691 |
| 19 | 2323474359 |
| 20 | 6971471651 |
| 21 | 20916512103 |
| 22 | 62753730611 |
| 23 | 188269580439 |
| 24 | 564825518531 |
| 25 | 1694510110023 |
| 26 | 5083597438931 |
| 27 | 15250926534519 |