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 | 1 |
| 1 | 9 |
| 2 | 60 |
| 3 | 360 |
| 4 | 2055 |
| 5 | 11403 |
| 6 | 62132 |
| 7 | 334260 |
| 8 | 1781415 |
| 9 | 9425295 |
| 10 | 49581576 |
| 11 | 259601004 |
| 12 | 1353939405 |
| 13 | 7038232425 |
| 14 | 36484340400 |
| 15 | 188665670880 |
| 16 | 973545780195 |
| 17 | 5014258620075 |
| 18 | 25783103206100 |
| 19 | 132378800689800 |
| 20 | 678768332410245 |
| 21 | 3476164133573505 |
| 22 | 17782899991147500 |