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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 8 |
| 5 | 20 |
| 6 | 48 |
| 7 | 136 |
| 8 | 360 |
| 9 | 1040 |
| 10 | 2944 |
| 11 | 8704 |
| 12 | 25280 |
| 13 | 76320 |
| 14 | 226720 |
| 15 | 692992 |
| 16 | 2096640 |
| 17 | 6470016 |
| 18 | 19799936 |
| 19 | 61713152 |
| 20 | 190683520 |
| 21 | 598033152 |
| 22 | 1863995392 |
| 23 | 5879859200 |
| 24 | 18438913536 |
| 25 | 58464724992 |
| 26 | 184356152832 |
| 27 | 586898946048 |
| 28 | 1859875518464 |
| 29 | 5941384080384 |
| 30 | 18901502482432 |