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 | 15 |
| 3 | 79 |
| 4 | 383 |
| 5 | 1727 |
| 6 | 7423 |
| 7 | 30975 |
| 8 | 126975 |
| 9 | 515071 |
| 10 | 2076671 |
| 11 | 8343551 |
| 12 | 33456127 |
| 13 | 134004735 |
| 14 | 536412159 |
| 15 | 2146500607 |
| 16 | 8587837439 |
| 17 | 34355281919 |
| 18 | 137429516287 |
| 19 | 549735890943 |
| 20 | 2198981312511 |
| 21 | 8796004941823 |
| 22 | 35184187539455 |
| 23 | 140737102479359 |
| 24 | 562949148114943 |
| 25 | 2251798135963647 |