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 | 38 |
| 5 | 645 |
| 6 | 7510 |
| 7 | 71981 |
| 8 | 617358 |
| 9 | 4947685 |
| 10 | 37972070 |
| 11 | 283229661 |
| 12 | 2072354878 |
| 13 | 14964711125 |
| 14 | 107078983830 |
| 15 | 761312910541 |
| 16 | 5388481567598 |
| 17 | 38017703680965 |
| 18 | 267622831854790 |
| 19 | 1880882526962621 |
| 20 | 13203901505935518 |
| 21 | 92616363612417205 |