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) |
|---|---|
| 4 | 1 |
| 5 | 3 |
| 6 | 19 |
| 7 | 128 |
| 8 | 909 |
| 9 | 6737 |
| 10 | 51683 |
| 11 | 407802 |
| 12 | 3293497 |
| 13 | 27122967 |
| 14 | 227095683 |
| 15 | 1928656876 |
| 16 | 16582719509 |
| 17 | 144125955717 |
| 18 | 1264625068163 |
| 19 | 11190598332502 |
| 20 | 99776445196977 |
| 21 | 895685185070155 |
| 22 | 8090065969366259 |
| 23 | 73480719648381240 |
| 24 | 670821169614526749 |