T(n, 2*n-4), T given by A027960.

Terms

a(0) =1a(1) =4a(2) =11a(3) =26a(4) =54a(5) =101a(6) =174a(7) =281a(8) =431a(9) =634a(10) =901a(11) =1244a(12) =1676a(13) =2211a(14) =2864a(15) =3651a(16) =4589a(17) =5696a(18) =6991a(19) =8494a(20) =10226a(21) =12209a(22) =14466a(23) =17021a(24) =19899a(25) =23126a(26) =26729a(27) =30736a(28) =35176a(29) =40079