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 | 9 |
| 3 | 27 |
| 4 | 77 |
| 5 | 207 |
| 6 | 529 |
| 7 | 1299 |
| 8 | 3093 |
| 9 | 7191 |
| 10 | 16409 |
| 11 | 36891 |
| 12 | 81949 |
| 13 | 180255 |
| 14 | 393249 |
| 15 | 852003 |
| 16 | 1835045 |
| 17 | 3932199 |
| 18 | 8388649 |
| 19 | 17825835 |
| 20 | 37748781 |
| 21 | 79691823 |
| 22 | 167772209 |
| 23 | 352321587 |
| 24 | 738197557 |
| 25 | 1543503927 |
| 26 | 3221225529 |
| 27 | 6710886459 |
| 28 | 13958643773 |
| 29 | 28991029311 |
| 30 | 60129542209 |