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 | 0 |
| 5 | 4 |
| 6 | 22 |
| 7 | 98 |
| 8 | 412 |
| 9 | 1700 |
| 10 | 6974 |
| 11 | 28576 |
| 12 | 117146 |
| 13 | 480722 |
| 14 | 1974914 |
| 15 | 8122084 |
| 16 | 33435390 |
| 17 | 137757480 |
| 18 | 567998152 |
| 19 | 2343472004 |
| 20 | 9674252070 |
| 21 | 39956606552 |
| 22 | 165099840920 |
| 23 | 682446679582 |
| 24 | 2821858504062 |
| 25 | 11671572244666 |
| 26 | 48287711006032 |
| 27 | 199822535773958 |
| 28 | 827069530795224 |
| 29 | 3423890026639184 |
| 30 | 14176516741276534 |