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 | 3 |
| 2 | 13 |
| 3 | 0 |
| 4 | 23252729 |
| 5 | 2527293133 |
| 6 | 0 |
| 7 | 57911131517 |
| 8 | 4547495153555759 |
| 9 | 0 |
| 10 | 135791113151719 |
| 11 | 87899193959799101103105107 |
| 12 | 0 |
| 13 | 23252729313335373941434547 |
| 14 | 357911131517192123252729 |
| 15 | 0 |