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 | 12 |
| 3 | 30 |
| 4 | 70 |
| 5 | 158 |
| 6 | 352 |
| 7 | 780 |
| 8 | 1724 |
| 9 | 3806 |
| 10 | 8398 |
| 11 | 18526 |
| 12 | 40864 |
| 13 | 90132 |
| 14 | 198796 |
| 15 | 438462 |
| 16 | 967062 |
| 17 | 2132926 |
| 18 | 4704320 |
| 19 | 10375708 |
| 20 | 22884348 |
| 21 | 50473022 |
| 22 | 111321758 |
| 23 | 245527870 |
| 24 | 541528768 |
| 25 | 1194379300 |
| 26 | 2634286476 |
| 27 | 5810101726 |
| 28 | 12814582758 |