T(n,n) + T(n,n+1) + ... + T(n,2n), T given by A027082.

Terms

a(0) =1a(1) =2a(2) =6a(3) =19a(4) =55a(5) =161a(6) =469a(7) =1362a(8) =3954a(9) =11483a(10) =33379a(11) =97146a(12) =283114a(13) =826214a(14) =2414366a(15) =7064217a(16) =20693797a(17) =60686847a(18) =178152055a(19) =523473326a(20) =1539479414a(21) =4531059224a(22) =13345835288a(23) =39335816471a(24) =116012701523a(25) =342356498884