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) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 4 |
| 4 | 14 |
| 5 | 72 |
| 6 | 370 |
| 7 | 1995 |
| 8 | 11064 |
| 9 | 62774 |
| 10 | 362614 |
| 11 | 2125479 |
| 12 | 12610410 |
| 13 | 75584363 |
| 14 | 457000668 |
| 15 | 2783991972 |
| 16 | 17071362986 |
| 17 | 105287143740 |
| 18 | 652687596388 |
| 19 | 4064618917998 |
| 20 | 25416557913498 |
| 21 | 159523021737403 |
| 22 | 1004594882114020 |
| 23 | 6345859437931884 |
| 24 | 40198433775513524 |