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 | 5 |
| 2 | 25 |
| 3 | 125 |
| 4 | 615 |
| 5 | 2995 |
| 6 | 14455 |
| 7 | 69235 |
| 8 | 329430 |
| 9 | 1558430 |
| 10 | 7334806 |
| 11 | 34364270 |
| 12 | 160340610 |
| 13 | 745362730 |
| 14 | 3453222850 |
| 15 | 15949215754 |
| 16 | 73454841775 |
| 17 | 337413819915 |
| 18 | 1546145183895 |
| 19 | 7068979186035 |
| 20 | 32251365241137 |
| 21 | 146853223312325 |
| 22 | 667445619383425 |