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 | 1 |
| 2 | 5 |
| 3 | 40 |
| 4 | 370 |
| 5 | 3740 |
| 6 | 40006 |
| 7 | 445231 |
| 8 | 5102165 |
| 9 | 59799505 |
| 10 | 713496815 |
| 11 | 8637432580 |
| 12 | 105826926716 |
| 13 | 1309793896431 |
| 14 | 16351672606365 |
| 15 | 205665994855320 |
| 16 | 2603696877136060 |
| 17 | 33151784577226295 |
| 18 | 424258396639960591 |
| 19 | 5454120586840761631 |
| 20 | 70402732493668027775 |