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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 19 |
| 5 | 317 |
| 6 | 5582 |
| 7 | 108244 |
| 8 | 2331108 |
| 9 | 55636986 |
| 10 | 1463717784 |
| 11 | 42182876763 |
| 12 | 1323539651164 |
| 13 | 44955519539963 |
| 14 | 1644461582317560 |
| 15 | 64481138409909506 |
| 16 | 2698923588248208224 |
| 17 | 120133276796015812548 |
| 18 | 5667351458582453925696 |
| 19 | 282496750694780020437765 |
| 20 | 14837506263979393796687088 |