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 | 17 |
| 3 | 83 |
| 4 | 417 |
| 5 | 2083 |
| 6 | 10417 |
| 7 | 52083 |
| 8 | 260417 |
| 9 | 1302083 |
| 10 | 6510417 |
| 11 | 32552083 |
| 12 | 162760417 |
| 13 | 813802083 |
| 14 | 4069010417 |
| 15 | 20345052083 |
| 16 | 101725260417 |
| 17 | 508626302083 |
| 18 | 2543131510417 |
| 19 | 12715657552083 |
| 20 | 63578287760417 |
| 21 | 317891438802083 |