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 | 2 |
| 2 | 6 |
| 3 | 18 |
| 4 | 50 |
| 5 | 130 |
| 6 | 322 |
| 7 | 770 |
| 8 | 1794 |
| 9 | 4098 |
| 10 | 9218 |
| 11 | 20482 |
| 12 | 45058 |
| 13 | 98306 |
| 14 | 212994 |
| 15 | 458754 |
| 16 | 983042 |
| 17 | 2097154 |
| 18 | 4456450 |
| 19 | 9437186 |
| 20 | 19922946 |
| 21 | 41943042 |
| 22 | 88080386 |
| 23 | 184549378 |
| 24 | 385875970 |
| 25 | 805306370 |
| 26 | 1677721602 |
| 27 | 3489660930 |
| 28 | 7247757314 |