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 | 0 |
| 2 | 2 |
| 3 | 12 |
| 4 | 42 |
| 5 | 115 |
| 6 | 288 |
| 7 | 738 |
| 8 | 2020 |
| 9 | 5751 |
| 10 | 16362 |
| 11 | 45697 |
| 12 | 125538 |
| 13 | 342318 |
| 14 | 933050 |
| 15 | 2547630 |
| 16 | 6960042 |
| 17 | 18990309 |
| 18 | 51699042 |
| 19 | 140439411 |
| 20 | 380871538 |
| 21 | 1031705466 |
| 22 | 2792009100 |
| 23 | 7548723827 |
| 24 | 20389716864 |
| 25 | 55020917232 |
| 26 | 148334534420 |
| 27 | 399562167420 |
| 28 | 1075432476492 |