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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 121 |
| 6 | 721 |
| 7 | 2521 |
| 8 | 6721 |
| 9 | 15121 |
| 10 | 1844641 |
| 11 | 20013841 |
| 12 | 119845441 |
| 13 | 519072841 |
| 14 | 1816454641 |
| 15 | 223394731561 |
| 16 | 3501661887361 |
| 17 | 29675906201761 |
| 18 | 177923109591361 |
| 19 | 844925253766561 |
| 20 | 104750282797418881 |