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) |
|---|---|
| 4 | 3 |
| 5 | 25 |
| 6 | 128 |
| 7 | 525 |
| 8 | 1901 |
| 9 | 6371 |
| 10 | 20291 |
| 11 | 62407 |
| 12 | 187272 |
| 13 | 552104 |
| 14 | 1606762 |
| 15 | 4631643 |
| 16 | 13256644 |
| 17 | 37742047 |
| 18 | 107025452 |
| 19 | 302585780 |
| 20 | 853556449 |
| 21 | 2403702976 |
| 22 | 6760469822 |
| 23 | 18995826302 |
| 24 | 53336990264 |
| 25 | 149680752886 |
| 26 | 419883986837 |
| 27 | 1177504825907 |
| 28 | 3301408010791 |
| 29 | 9254726751126 |