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 | 4 |
| 1 | 19 |
| 2 | 79 |
| 3 | 319 |
| 4 | 1279 |
| 5 | 5119 |
| 6 | 20479 |
| 7 | 81919 |
| 8 | 327679 |
| 9 | 1310719 |
| 10 | 5242879 |
| 11 | 20971519 |
| 12 | 83886079 |
| 13 | 335544319 |
| 14 | 1342177279 |
| 15 | 5368709119 |
| 16 | 21474836479 |
| 17 | 85899345919 |
| 18 | 343597383679 |
| 19 | 1374389534719 |
| 20 | 5497558138879 |
| 21 | 21990232555519 |
| 22 | 87960930222079 |
| 23 | 351843720888319 |