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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 3 |
| 5 | 11 |
| 6 | 65 |
| 7 | 287 |
| 8 | 1373 |
| 9 | 6370 |
| 10 | 30149 |
| 11 | 142638 |
| 12 | 681520 |
| 13 | 3270604 |
| 14 | 15789461 |
| 15 | 76562081 |
| 16 | 372832744 |
| 17 | 1822142769 |
| 18 | 8934740804 |
| 19 | 43938715224 |
| 20 | 216650217219 |
| 21 | 1070791145115 |
| 22 | 5303851997213 |
| 23 | 26323053574543 |
| 24 | 130878372709130 |
| 25 | 651812928565763 |
| 26 | 3251215398061949 |
| 27 | 16240020484212325 |
| 28 | 81227147300622466 |
| 29 | 406770969577924068 |
| 30 | 2039375196443918387 |