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 | 5 |
| 2 | 25 |
| 3 | 124 |
| 4 | 615 |
| 5 | 3050 |
| 6 | 15126 |
| 7 | 75015 |
| 8 | 372025 |
| 9 | 1844999 |
| 10 | 9149980 |
| 11 | 45377875 |
| 12 | 225044376 |
| 13 | 1116071900 |
| 14 | 5534981625 |
| 15 | 27449863749 |
| 16 | 136133246845 |
| 17 | 675131252600 |
| 18 | 3348206399251 |
| 19 | 16604898749410 |
| 20 | 82349362494450 |
| 21 | 408398606072999 |