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 | 15 |
| 5 | 232 |
| 6 | 3945 |
| 7 | 75197 |
| 8 | 1604974 |
| 9 | 38122542 |
| 10 | 1000354710 |
| 11 | 28790664534 |
| 12 | 902783451933 |
| 13 | 30658102047787 |
| 14 | 1121532291098765 |
| 15 | 43985781899812395 |
| 16 | 1841621373756094796 |
| 17 | 82002075703514947236 |
| 18 | 3869941339069299799884 |
| 19 | 192976569550677042208068 |
| 20 | 10139553075163838030949495 |