A026884 T(2n,n+2), T given by A026769.
1, 6, 29, 132, 591, 2648, 11970, 54818, 254868, 1204042, 5779861, 28178306, 139394333, 698911166, 3547422416, 18204441884, 94339586414, 493148411592, 2597699326194, 13776442755524, 73498738275926, 394203045846692
Offset: 2