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 | 15 |
| 2 | 27 |
| 3 | 57 |
| 4 | 135 |
| 5 | 345 |
| 6 | 927 |
| 7 | 2577 |
| 8 | 7335 |
| 9 | 21225 |
| 10 | 62127 |
| 11 | 183297 |
| 12 | 543735 |
| 13 | 1618905 |
| 14 | 4832127 |
| 15 | 14447217 |
| 16 | 43243335 |
| 17 | 129533385 |
| 18 | 388206927 |
| 19 | 1163834337 |
| 20 | 3489930135 |
| 21 | 10466644665 |
| 22 | 31393642527 |
| 23 | 94168344657 |
| 24 | 282479868135 |