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 | 10 |
| 3 | 54 |
| 4 | 238 |
| 5 | 990 |
| 6 | 4030 |
| 7 | 16254 |
| 8 | 65278 |
| 9 | 261630 |
| 10 | 1047550 |
| 11 | 4192254 |
| 12 | 16773118 |
| 13 | 67100670 |
| 14 | 268419070 |
| 15 | 1073709054 |
| 16 | 4294901758 |
| 17 | 17179738110 |
| 18 | 68719214590 |
| 19 | 274877382654 |
| 20 | 1099510579198 |
| 21 | 4398044413950 |
| 22 | 17592181850110 |
| 23 | 70368735789054 |
| 24 | 281474959933438 |
| 25 | 1125899873288190 |