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 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 17 |
| 5 | 49 |
| 6 | 127 |
| 7 | 337 |
| 8 | 881 |
| 9 | 2311 |
| 10 | 6049 |
| 11 | 15841 |
| 12 | 41471 |
| 13 | 108577 |
| 14 | 284257 |
| 15 | 744199 |
| 16 | 1948337 |
| 17 | 5100817 |
| 18 | 13354111 |
| 19 | 34961521 |
| 20 | 91530449 |
| 21 | 239629831 |
| 22 | 627359041 |
| 23 | 1642447297 |
| 24 | 4299982847 |
| 25 | 11257501249 |
| 26 | 29472520897 |
| 27 | 77160061447 |
| 28 | 202007663441 |
| 29 | 528862928881 |
| 30 | 1384581123199 |