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 | 3 |
| 2 | 15 |
| 3 | 165 |
| 4 | 4845 |
| 5 | 435897 |
| 6 | 131115985 |
| 7 | 138432467745 |
| 8 | 525783425977953 |
| 9 | 7271150092378906305 |
| 10 | 368539102493388126164865 |
| 11 | 68777035446753808820521420545 |
| 12 | 47450879627176629761462147774626305 |