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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 2 |
| 8 | 6 |
| 9 | 18 |
| 10 | 61 |
| 11 | 225 |
| 12 | 901 |
| 13 | 3905 |
| 14 | 18226 |
| 15 | 91134 |
| 16 | 486048 |
| 17 | 2754274 |
| 18 | 16525645 |
| 19 | 104662422 |
| 20 | 697749481 |
| 21 | 4884246371 |
| 22 | 35817806721 |
| 23 | 274603184861 |
| 24 | 2196825478892 |
| 25 | 18306878990770 |
| 26 | 158659617920008 |
| 27 | 1427936561280078 |
| 28 | 13327407905280733 |
| 29 | 128831609751047086 |