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) |
|---|---|
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 4 |
| 6 | 17 |
| 7 | 66 |
| 8 | 269 |
| 9 | 1102 |
| 10 | 4635 |
| 11 | 19768 |
| 12 | 85659 |
| 13 | 375524 |
| 14 | 1664015 |
| 15 | 7438862 |
| 16 | 33515027 |
| 17 | 152016610 |
| 18 | 693622315 |
| 19 | 3181516040 |
| 20 | 14661568795 |
| 21 | 67850245684 |
| 22 | 315187594779 |
| 23 | 1469195413102 |
| 24 | 6869889480447 |
| 25 | 32215398047474 |
| 26 | 151467333043437 |
| 27 | 713881813137776 |
| 28 | 3372142135461789 |