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 | 4 |
| 2 | 15 |
| 3 | 52 |
| 4 | 175 |
| 5 | 582 |
| 6 | 1927 |
| 7 | 6370 |
| 8 | 21045 |
| 9 | 69514 |
| 10 | 229597 |
| 11 | 758316 |
| 12 | 2504557 |
| 13 | 8272000 |
| 14 | 27320571 |
| 15 | 90233728 |
| 16 | 298021771 |
| 17 | 984299058 |
| 18 | 3250918963 |
| 19 | 10737055966 |
| 20 | 35462086881 |
| 21 | 117123316630 |
| 22 | 386832036793 |
| 23 | 1277619427032 |
| 24 | 4219690317913 |