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 | 5 |
| 1 | 21 |
| 2 | 105 |
| 3 | 595 |
| 4 | 3675 |
| 5 | 24150 |
| 6 | 166257 |
| 7 | 1186680 |
| 8 | 8717940 |
| 9 | 65572325 |
| 10 | 502957455 |
| 11 | 3922142574 |
| 12 | 31021294850 |
| 13 | 248377859100 |
| 14 | 2010068042625 |
| 15 | 16421073515280 |
| 16 | 135277629836412 |
| 17 | 1122788441510820 |
| 18 | 9381874768828100 |
| 19 | 78871575753345375 |
| 20 | 666727830129370275 |