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 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 20 |
| 6 | 60 |
| 7 | 204 |
| 8 | 702 |
| 9 | 2526 |
| 10 | 9180 |
| 11 | 33989 |
| 12 | 126713 |
| 13 | 476597 |
| 14 | 1802109 |
| 15 | 6850969 |
| 16 | 26151529 |
| 17 | 100207548 |
| 18 | 385217382 |
| 19 | 1485216987 |
| 20 | 5741240989 |
| 21 | 22246000726 |
| 22 | 86383317470 |
| 23 | 336093551268 |
| 24 | 1309997856337 |
| 25 | 5114452295933 |
| 26 | 19998171631076 |
| 27 | 78306014924606 |
| 28 | 307022177714062 |