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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 36 |
| 5 | 111 |
| 6 | 344 |
| 7 | 1064 |
| 8 | 3288 |
| 9 | 10161 |
| 10 | 31404 |
| 11 | 97060 |
| 12 | 299980 |
| 13 | 927135 |
| 14 | 2865456 |
| 15 | 8856144 |
| 16 | 27371312 |
| 17 | 84595361 |
| 18 | 261455316 |
| 19 | 808068924 |
| 20 | 2497464564 |
| 21 | 7718808463 |
| 22 | 23856195976 |
| 23 | 73731339384 |
| 24 | 227878342920 |
| 25 | 704293989585 |
| 26 | 2176731748220 |
| 27 | 6727533066836 |
| 28 | 20792502889884 |