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 | 12 |
| 3 | 36 |
| 4 | 144 |
| 5 | 276 |
| 6 | 2124 |
| 7 | 2796 |
| 8 | 17760 |
| 9 | 44184 |
| 10 | 263004 |
| 11 | 419868 |
| 12 | 4278000 |
| 13 | 5593996 |
| 14 | 44748804 |
| 15 | 134390724 |
| 16 | 539036160 |
| 17 | 1073758356 |
| 18 | 11453725416 |
| 19 | 15271054956 |
| 20 | 137575549680 |
| 21 | 366528035564 |
| 22 | 1759219864020 |
| 23 | 3198580043436 |