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) |
|---|---|
| 18 | 1 |
| 19 | 19 |
| 20 | 190 |
| 21 | 1330 |
| 22 | 7315 |
| 23 | 33649 |
| 24 | 134596 |
| 25 | 480700 |
| 26 | 1562275 |
| 27 | 4686825 |
| 28 | 13123110 |
| 29 | 34597290 |
| 30 | 86493225 |
| 31 | 206253075 |
| 32 | 471435600 |
| 33 | 1037158320 |
| 34 | 2203961430 |
| 35 | 4537567650 |
| 36 | 9075135300 |
| 37 | 17672631900 |
| 38 | 33578000610 |
| 39 | 62359143990 |
| 40 | 113380261800 |
| 41 | 202112640600 |
| 42 | 353697121050 |
| 43 | 608359048206 |