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 | 0 |
| 4 | 4 |
| 5 | 55 |
| 6 | 396 |
| 7 | 2114 |
| 8 | 9528 |
| 9 | 38637 |
| 10 | 146080 |
| 11 | 526240 |
| 12 | 1831644 |
| 13 | 6217523 |
| 14 | 20716164 |
| 15 | 68059710 |
| 16 | 221195824 |
| 17 | 712856665 |
| 18 | 2282058360 |
| 19 | 7266358556 |
| 20 | 23035517940 |
| 21 | 72760054815 |
| 22 | 229112753980 |
| 23 | 719545590010 |
| 24 | 2254604460264 |
| 25 | 7050252659525 |
| 26 | 22006821057936 |
| 27 | 68581455012504 |
| 28 | 213411502891468 |