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 | 34 |
| 3 | 494 |
| 4 | 8615 |
| 5 | 165550 |
| 6 | 3380923 |
| 7 | 71999763 |
| 8 | 1580990725 |
| 9 | 35537491360 |
| 10 | 813691565184 |
| 11 | 18911247654404 |
| 12 | 444978958424224 |
| 13 | 10579389908116344 |
| 14 | 253756528273411250 |
| 15 | 6133110915783398175 |
| 16 | 149219383150626519874 |
| 17 | 3651756292682801022384 |
| 18 | 89830021324956206790496 |
| 19 | 2219945238901447637080235 |
| 20 | 55088272581138888326634644 |