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) |
|---|---|
| 3 | 1 |
| 4 | 5 |
| 5 | 18 |
| 6 | 57 |
| 7 | 169 |
| 8 | 482 |
| 9 | 1341 |
| 10 | 3669 |
| 11 | 9922 |
| 12 | 26609 |
| 13 | 70929 |
| 14 | 188226 |
| 15 | 497845 |
| 16 | 1313501 |
| 17 | 3459042 |
| 18 | 9096393 |
| 19 | 23895673 |
| 20 | 62721698 |
| 21 | 164531565 |
| 22 | 431397285 |
| 23 | 1130708866 |
| 24 | 2962826465 |
| 25 | 7761964833 |
| 26 | 20331456642 |
| 27 | 53249182309 |
| 28 | 139449644717 |
| 29 | 365166860706 |
| 30 | 956185155129 |
| 31 | 2503657040137 |