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 | 3 |
| 1 | 7 |
| 2 | 27 |
| 3 | 127 |
| 4 | 627 |
| 5 | 3127 |
| 6 | 15627 |
| 7 | 78127 |
| 8 | 390627 |
| 9 | 1953127 |
| 10 | 9765627 |
| 11 | 48828127 |
| 12 | 244140627 |
| 13 | 1220703127 |
| 14 | 6103515627 |
| 15 | 30517578127 |
| 16 | 152587890627 |
| 17 | 762939453127 |
| 18 | 3814697265627 |
| 19 | 19073486328127 |
| 20 | 95367431640627 |
| 21 | 476837158203127 |
| 22 | 2384185791015627 |
| 23 | 11920928955078127 |