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 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 49 |
| 5 | 121 |
| 6 | 2701 |
| 7 | 5041 |
| 8 | 219521 |
| 9 | 1587601 |
| 10 | 33446701 |
| 11 | 39916801 |
| 12 | 17731796545 |
| 13 | 6227020801 |
| 14 | 2879710009177 |
| 15 | 98069239768501 |
| 16 | 2418218838097921 |
| 17 | 355687428096001 |
| 18 | 2832293713653708877 |
| 19 | 121645100408832001 |
| 20 | 2295597943489176040001 |
| 21 | 71029619657111138063041 |