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 | 95 |
| 3 | 433 |
| 4 | 1975 |
| 5 | 9009 |
| 6 | 41095 |
| 7 | 187457 |
| 8 | 855095 |
| 9 | 3900561 |
| 10 | 17792615 |
| 11 | 81161953 |
| 12 | 370224535 |
| 13 | 1688798769 |
| 14 | 7703544775 |
| 15 | 35140126337 |
| 16 | 160293542135 |
| 17 | 731187458001 |
| 18 | 3335350205735 |
| 19 | 15214376112673 |
| 20 | 69401180151895 |
| 21 | 316577148534129 |