A027090 a(n) = A027082(n, 2n-3).
1, 3, 9, 28, 84, 246, 714, 2059, 5917, 16971, 48633, 139333, 399267, 1144669, 3283839, 9427981, 27090715, 77911897, 224272499, 646157234, 1863317958, 5377939756, 15535195892, 44913790501, 129955421387, 376313609029
Offset: 2