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 | -1 |
| 3 | 2 |
| 4 | -1 |
| 5 | 5 |
| 6 | 6 |
| 7 | 17 |
| 8 | 27 |
| 9 | 58 |
| 10 | 111 |
| 11 | 229 |
| 12 | 454 |
| 13 | 913 |
| 14 | 1819 |
| 15 | 3642 |
| 16 | 7279 |
| 17 | 14565 |
| 18 | 29126 |
| 19 | 58257 |
| 20 | 116507 |
| 21 | 233018 |
| 22 | 466031 |
| 23 | 932069 |
| 24 | 1864134 |
| 25 | 3728273 |
| 26 | 7456539 |
| 27 | 14913082 |
| 28 | 29826159 |
| 29 | 59652325 |
| 30 | 119304646 |
| 31 | 238609297 |
| 32 | 477218587 |
| 33 | 954437178 |
| 34 | 1908874351 |
| 35 | 3817748709 |
| 36 | 7635497414 |