A027098 T(n,n) + T(n,n+1) + ... + T(n,2n), T given by A027082.
1, 2, 6, 19, 55, 161, 469, 1362, 3954, 11483, 33379, 97146, 283114, 826214, 2414366, 7064217, 20693797, 60686847, 178152055, 523473326, 1539479414, 4531059224, 13345835288, 39335816471, 116012701523, 342356498884
Offset: 0