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 | 3 |
| 2 | 7 |
| 3 | 18 |
| 4 | 49 |
| 5 | 138 |
| 6 | 397 |
| 7 | 1158 |
| 8 | 3409 |
| 9 | 10098 |
| 10 | 30037 |
| 11 | 89598 |
| 12 | 267769 |
| 13 | 801258 |
| 14 | 2399677 |
| 15 | 7190838 |
| 16 | 21556129 |
| 17 | 64635618 |
| 18 | 193841317 |
| 19 | 581392878 |
| 20 | 1743916489 |
| 21 | 5231225178 |
| 22 | 15692626957 |
| 23 | 47075783718 |
| 24 | 141223156849 |
| 25 | 423661081938 |
| 26 | 1270966468597 |
| 27 | 3812865851358 |
| 28 | 11438530445209 |
| 29 | 34315457117898 |
| 30 | 102946102918237 |