T(n, 2*n-3), T given by A027960.

Terms

a(0) =3a(1) =7a(2) =15a(3) =28a(4) =47a(5) =73a(6) =107a(7) =150a(8) =203a(9) =267a(10) =343a(11) =432a(12) =535a(13) =653a(14) =787a(15) =938a(16) =1107a(17) =1295a(18) =1503a(19) =1732a(20) =1983a(21) =2257a(22) =2555a(23) =2878a(24) =3227a(25) =3603a(26) =4007a(27) =4440a(28) =4903a(29) =5397