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 | 3 |
| 2 | 7 |
| 3 | 19 |
| 4 | 63 |
| 5 | 231 |
| 6 | 895 |
| 7 | 3615 |
| 8 | 15055 |
| 9 | 64111 |
| 10 | 277791 |
| 11 | 1220767 |
| 12 | 5427775 |
| 13 | 24371199 |
| 14 | 110350335 |
| 15 | 503289727 |
| 16 | 2309992959 |
| 17 | 10661634303 |
| 18 | 49452179455 |
| 19 | 230391918591 |
| 20 | 1077644520703 |
| 21 | 5058766156543 |
| 22 | 23824929459711 |
| 23 | 112541456498175 |
| 24 | 533063457631231 |
| 25 | 2531252417738751 |