Diagonal sum of left-justified array T given by A027023.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =3a(5) =6a(6) =7a(7) =11a(8) =16a(9) =21a(10) =33a(11) =48a(12) =65a(13) =101a(14) =146a(15) =203a(16) =311a(17) =450a(18) =635a(19) =963a(20) =1396a(21) =1989a(22) =2993a(23) =4348a(24) =6233a(25) =9329a(26) =13574a(27) =19543a(28) =29135a(29) =42446