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) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 13 |
| 5 | 42 |
| 6 | 148 |
| 7 | 540 |
| 8 | 1945 |
| 9 | 6994 |
| 10 | 25784 |
| 11 | 96564 |
| 12 | 361560 |
| 13 | 1353608 |
| 14 | 5113044 |
| 15 | 19462184 |
| 16 | 74227737 |
| 17 | 283335006 |
| 18 | 1085696746 |
| 19 | 4176869836 |
| 20 | 16100775648 |
| 21 | 62132631186 |
| 22 | 240258482330 |
| 23 | 931152718588 |
| 24 | 3614359486290 |
| 25 | 14044139747816 |