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 | 4 |
| 2 | 19 |
| 3 | 109 |
| 4 | 739 |
| 5 | 5779 |
| 6 | 51139 |
| 7 | 504739 |
| 8 | 5494339 |
| 9 | 65369539 |
| 10 | 843747139 |
| 11 | 11741033539 |
| 12 | 175200329539 |
| 13 | 2790549065539 |
| 14 | 47251477577539 |
| 15 | 847548190793539 |
| 16 | 16053185741897539 |
| 17 | 320165936763977539 |
| 18 | 6706533708227657539 |
| 19 | 147206624680428617539 |
| 20 | 3378708717041050697539 |