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 | 1 |
| 2 | 8 |
| 3 | 45 |
| 4 | 416 |
| 5 | 1685 |
| 6 | 31032 |
| 7 | 229026 |
| 8 | 13856896 |
| 9 | 132843888 |
| 10 | 6551143600 |
| 11 | 672567897859 |
| 12 | 346984064352 |
| 13 | 51233511973865 |
| 14 | 99704578224832 |
| 15 | 1521740934249300 |
| 16 | 87595020192056292864 |
| 17 | 81891555365769626429 |
| 18 | 12883000343953567644 |
| 19 | 318718123756704667891346 |
| 20 | 50107182570391966040000 |
| 21 | 500792393469899639083500 |