The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 12 |
| 3 | 36 |
| 4 | 108 |
| 5 | 324 |
| 6 | 972 |
| 7 | 2916 |
| 8 | 8748 |
| 9 | 26244 |
| 10 | 78732 |
| 11 | 236196 |
| 12 | 708582 |
| 13 | 2125728 |
| 14 | 6377136 |
| 15 | 19131264 |
| 16 | 57393360 |
| 17 | 172178784 |
| 18 | 516532464 |
| 19 | 1549585728 |
| 20 | 4648722192 |
| 21 | 13946061600 |
| 22 | 41837869872 |
| 23 | 125512664832 |
| 24 | 376535160174 |
| 25 | 1129596977628 |
[1,4,12,36,108,324,972,2916,8748,26244,78732, 236196,708582,2125728,6377136,19131264,57393360, 172178784,516532464,1549585728,4648722192, 13946061600,41837869872,125512664832,376535160174, 1129596977628] |