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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 39 |
| 6 | 167 |
| 7 | 660 |
| 8 | 3083 |
| 9 | 13961 |
| 10 | 70728 |
| 11 | 355457 |
| 12 | 1936449 |
| 13 | 10587960 |
| 14 | 61539129 |
| 15 | 361182139 |
| 16 | 2224641540 |
| 17 | 13880534119 |
| 18 | 90090083047 |
| 19 | 593246514588 |
| 20 | 4038095508691 |
| 21 | 27905008440273 |
| 22 | 198401618299920 |
| 23 | 1432253086621377 |
| 24 | 10600146578310209 |
| 25 | 79639887325700592 |
| 26 | 611739960145556273 |