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 | 121 |
| 4 | 1333 |
| 5 | 18091 |
| 6 | 286867 |
| 7 | 5158385 |
| 8 | 103226313 |
| 9 | 2269474723 |
| 10 | 54307112951 |
| 11 | 1404350909545 |
| 12 | 39020894189245 |
| 13 | 1159475912653163 |
| 14 | 36695329075865083 |
| 15 | 1232560854783934561 |
| 16 | 43801551907551784721 |
| 17 | 1642199848241650875907 |
| 18 | 64789265823476378293855 |