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 | 3 |
| 4 | 9 |
| 5 | 25 |
| 6 | 69 |
| 7 | 189 |
| 8 | 518 |
| 9 | 1422 |
| 10 | 3915 |
| 11 | 10813 |
| 12 | 29964 |
| 13 | 83304 |
| 14 | 232323 |
| 15 | 649845 |
| 16 | 1822824 |
| 17 | 5126520 |
| 18 | 14453451 |
| 19 | 40843521 |
| 20 | 115668105 |
| 21 | 328233969 |
| 22 | 933206967 |
| 23 | 2657946907 |
| 24 | 7583013474 |
| 25 | 21668135850 |
| 26 | 62007732605 |
| 27 | 177696228411 |
| 28 | 509899901553 |
| 29 | 1464990733969 |
| 30 | 4214045993925 |