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 | 7 |
| 2 | 29 |
| 3 | 125 |
| 4 | 543 |
| 5 | 2363 |
| 6 | 10287 |
| 7 | 44787 |
| 8 | 194995 |
| 9 | 848979 |
| 10 | 3696331 |
| 11 | 16093291 |
| 12 | 70067867 |
| 13 | 305065387 |
| 14 | 1328210699 |
| 15 | 5782837835 |
| 16 | 25177641963 |
| 17 | 109619822123 |
| 18 | 477268896747 |
| 19 | 2077959947307 |
| 20 | 9047137938475 |
| 21 | 39389933855019 |