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) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 17 |
| 4 | 128 |
| 5 | 1131 |
| 6 | 11070 |
| 7 | 116317 |
| 8 | 1287480 |
| 9 | 14829188 |
| 10 | 176250143 |
| 11 | 2148687567 |
| 12 | 26750057584 |
| 13 | 338939419026 |
| 14 | 4359422270652 |
| 15 | 56799490825125 |
| 16 | 748414965684808 |
| 17 | 9959308633462092 |
| 18 | 133694287642377756 |
| 19 | 1808762770097970724 |
| 20 | 24642635223262953600 |
| 21 | 337856475305856870275 |