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) |
|---|---|
| 1 | 4 |
| 2 | 60 |
| 3 | 840 |
| 4 | 11704 |
| 5 | 163020 |
| 6 | 2270580 |
| 7 | 31625104 |
| 8 | 440480880 |
| 9 | 6135107220 |
| 10 | 85451020204 |
| 11 | 1190179175640 |
| 12 | 16577057438760 |
| 13 | 230888624967004 |
| 14 | 3215863692099300 |
| 15 | 44791203064423200 |
| 16 | 623860979209825504 |
| 17 | 8689262505873133860 |
| 18 | 121025814103014048540 |
| 19 | 1685672134936323545704 |