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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 6 |
| 6 | 6 |
| 7 | 36 |
| 8 | 36 |
| 9 | 150 |
| 10 | 144 |
| 11 | 540 |
| 12 | 534 |
| 13 | 1806 |
| 14 | 1770 |
| 15 | 5790 |
| 16 | 5760 |
| 17 | 18150 |
| 18 | 17994 |
| 19 | 55980 |
| 20 | 55830 |
| 21 | 170970 |
| 22 | 170466 |
| 23 | 519156 |
| 24 | 518580 |
| 25 | 1569744 |
| 26 | 1567944 |
| 27 | 4733670 |
| 28 | 4732014 |
| 29 | 14250606 |
| 30 | 14244660 |
| 31 | 42850116 |
| 32 | 42844320 |
| 33 | 128746410 |
| 34 | 128728800 |