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 | 3 |
| 2 | 9 |
| 3 | 45 |
| 4 | 246 |
| 5 | 1485 |
| 6 | 9432 |
| 7 | 62625 |
| 8 | 428319 |
| 9 | 3000393 |
| 10 | 21410436 |
| 11 | 155106693 |
| 12 | 1137703869 |
| 13 | 8432624850 |
| 14 | 63060142671 |
| 15 | 475196487363 |
| 16 | 3604851603690 |
| 17 | 27507181503069 |
| 18 | 210988219961637 |
| 19 | 1625848092941463 |
| 20 | 12580709718788622 |
| 21 | 97714211996345868 |
| 22 | 761528782558088202 |