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 | 4 |
| 2 | 19 |
| 3 | 106 |
| 4 | 685 |
| 5 | 5056 |
| 6 | 42079 |
| 7 | 390454 |
| 8 | 4000441 |
| 9 | 44881660 |
| 10 | 547457611 |
| 11 | 7215589954 |
| 12 | 102211815589 |
| 13 | 1548801969976 |
| 14 | 25000879886935 |
| 15 | 428332610385166 |
| 16 | 7763306399014129 |
| 17 | 148412806214119924 |
| 18 | 2984692721713278211 |