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 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 61 |
| 5 | 341 |
| 6 | 2221 |
| 7 | 16045 |
| 8 | 127065 |
| 9 | 1097353 |
| 10 | 10231561 |
| 11 | 102133241 |
| 12 | 1085537509 |
| 13 | 12228389629 |
| 14 | 145369356861 |
| 15 | 1816987580101 |
| 16 | 23804010114481 |
| 17 | 325966118893457 |
| 18 | 4654236956576977 |
| 19 | 69138950655122929 |
| 20 | 1066449047096819901 |
| 21 | 17050138691821539781 |