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 | 5 |
| 3 | 34 |
| 4 | 253 |
| 5 | 2024 |
| 6 | 16867 |
| 7 | 144575 |
| 8 | 1265032 |
| 9 | 11235584 |
| 10 | 101120256 |
| 11 | 919272960 |
| 12 | 8342666880 |
| 13 | 77009232720 |
| 14 | 715008573240 |
| 15 | 6667341335024 |
| 16 | 62500632501585 |
| 17 | 588241236472080 |
| 18 | 5555611677791867 |
| 19 | 52632110631712424 |
| 20 | 500005051001268028 |