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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 11 |
| 7 | 33 |
| 8 | 137 |
| 9 | 478 |
| 10 | 1851 |
| 11 | 6845 |
| 12 | 26148 |
| 13 | 98406 |
| 14 | 374010 |
| 15 | 1416251 |
| 16 | 5380907 |
| 17 | 20440250 |
| 18 | 77795428 |
| 19 | 296384565 |
| 20 | 1131011633 |
| 21 | 4321964768 |
| 22 | 16541275068 |
| 23 | 63400061153 |
| 24 | 243358803904 |
| 25 | 935431121462 |
| 26 | 3600520831215 |
| 27 | 13876485252323 |
| 28 | 53546253055179 |
| 29 | 206864927506166 |
| 30 | 800068244639812 |