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 | 6 |
| 2 | 20 |
| 3 | 52 |
| 4 | 120 |
| 5 | 260 |
| 6 | 544 |
| 7 | 1116 |
| 8 | 2264 |
| 9 | 4564 |
| 10 | 9168 |
| 11 | 18380 |
| 12 | 36808 |
| 13 | 73668 |
| 14 | 147392 |
| 15 | 294844 |
| 16 | 589752 |
| 17 | 1179572 |
| 18 | 2359216 |
| 19 | 4718508 |
| 20 | 9437096 |
| 21 | 18874276 |
| 22 | 37748640 |
| 23 | 75497372 |
| 24 | 150994840 |
| 25 | 301989780 |
| 26 | 603979664 |
| 27 | 1207959436 |
| 28 | 2415918984 |