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) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 30 |
| 3 | 138 |
| 4 | 606 |
| 5 | 2586 |
| 6 | 10818 |
| 7 | 44574 |
| 8 | 181542 |
| 9 | 732678 |
| 10 | 2935218 |
| 11 | 11687202 |
| 12 | 46296210 |
| 13 | 182588850 |
| 14 | 717395262 |
| 15 | 2809372302 |
| 16 | 10969820358 |
| 17 | 42724062966 |
| 18 | 166015496838 |
| 19 | 643768299018 |
| 20 | 2491738141314 |
| 21 | 9628130289018 |
| 22 | 37146098272266 |
| 23 | 143110933254702 |
| 24 | 550643544948090 |