A026912 T(2n-1,n-1), T given by A026907.
13, 90, 370, 1403, 5256, 19749, 74628, 283551, 1082440, 4148594, 15953598, 61526960, 237876562, 921678867, 3577968072, 13913243127, 54184698792, 211307360862, 825059443542, 3225071709972, 12619275028602, 49423455006492
Offset: 1