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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 33 |
| 5 | 135 |
| 6 | 633 |
| 7 | 3207 |
| 8 | 17589 |
| 9 | 102627 |
| 10 | 636032 |
| 11 | 4161120 |
| 12 | 28680366 |
| 13 | 207313084 |
| 14 | 1567270962 |
| 15 | 12344164132 |
| 16 | 101000981146 |
| 17 | 856048842064 |
| 18 | 7499822589206 |
| 19 | 67789041509948 |
| 20 | 631233681093760 |
| 21 | 6047600235405942 |
| 22 | 59548341631378238 |
| 23 | 602020901133491946 |
| 24 | 6243160989929600212 |