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 | 0 |
| 1 | 3 |
| 2 | 62 |
| 3 | 1021 |
| 4 | 16380 |
| 5 | 262143 |
| 6 | 4194298 |
| 7 | 67108857 |
| 8 | 1073741816 |
| 9 | 17179869179 |
| 10 | 274877906934 |
| 11 | 4398046511093 |
| 12 | 70368744177652 |
| 13 | 1125899906842615 |
| 14 | 18014398509481970 |
| 15 | 288230376151711729 |
| 16 | 4611686018427387888 |
| 17 | 73786976294838206451 |
| 18 | 1180591620717411303406 |
| 19 | 18889465931478580854765 |