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 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 4 |
| 6 | 17 |
| 7 | 68 |
| 8 | 267 |
| 9 | 1041 |
| 10 | 4049 |
| 11 | 15739 |
| 12 | 61194 |
| 13 | 238081 |
| 14 | 927071 |
| 15 | 3613362 |
| 16 | 14097113 |
| 17 | 55050810 |
| 18 | 215178232 |
| 19 | 841813885 |
| 20 | 3296075636 |
| 21 | 12915801131 |
| 22 | 50648751006 |
| 23 | 198756000104 |
| 24 | 780472848048 |
| 25 | 3066651564995 |
| 26 | 12056585499217 |
| 27 | 47426685674204 |
| 28 | 186657789816391 |
| 29 | 734990466616069 |