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 | 84 |
| 2 | 336 |
| 3 | 1344 |
| 4 | 5040 |
| 5 | 19374 |
| 6 | 75180 |
| 7 | 289248 |
| 8 | 1113348 |
| 9 | 4294574 |
| 10 | 16553380 |
| 11 | 63784786 |
| 12 | 245853464 |
| 13 | 947613919 |
| 14 | 3652200016 |
| 15 | 14076313291 |
| 16 | 54253546534 |
| 17 | 209104275023 |
| 18 | 805930938847 |
| 19 | 3106231773354 |
| 20 | 11972077046301 |
| 21 | 46142909963825 |