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 | 115 |
| 4 | 515 |
| 5 | 2285 |
| 6 | 10119 |
| 7 | 44901 |
| 8 | 200119 |
| 9 | 897301 |
| 10 | 4052183 |
| 11 | 18444197 |
| 12 | 84651063 |
| 13 | 391805877 |
| 14 | 1828676887 |
| 15 | 8604122053 |
| 16 | 40793238647 |
| 17 | 194778656213 |
| 18 | 936040595031 |
| 19 | 4524410973669 |
| 20 | 21981448319671 |
| 21 | 107275320299509 |
| 22 | 525571712299415 |