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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 15 |
| 5 | 0 |
| 6 | 63 |
| 7 | 729 |
| 8 | 195 |
| 9 | 96393124 |
| 10 | 0 |
| 11 | 59049 |
| 12 | 0 |
| 13 | 0 |
| 14 | 0 |
| 15 | 58564 |
| 16 | 65535 |
| 17 | 0 |
| 18 | 0 |
| 19 | 0 |
| 20 | 18224 |
| 21 | 339086603837890624 |
| 22 | 0 |
| 23 | 302862043149743582494593171234930481 |
| 24 | 456975 |
| 25 | 4785795436938284970984441531228412302268149380473357781656407371343376 |
| 26 | 0 |
| 27 | 8990453124 |
| 28 | 0 |
| 29 | 0 |
| 30 | 0 |