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 | 4 |
| 2 | 14 |
| 3 | 50 |
| 4 | 180 |
| 5 | 650 |
| 6 | 2350 |
| 7 | 8500 |
| 8 | 30750 |
| 9 | 111250 |
| 10 | 402500 |
| 11 | 1456250 |
| 12 | 5268750 |
| 13 | 19062500 |
| 14 | 68968750 |
| 15 | 249531250 |
| 16 | 902812500 |
| 17 | 3266406250 |
| 18 | 11817968750 |
| 19 | 42757812500 |
| 20 | 154699218750 |
| 21 | 559707031250 |
| 22 | 2025039062500 |
| 23 | 7326660156250 |
| 24 | 26508105468750 |