t(n)_n where t() = triangular numbers A000217.

Terms

a(0) =1a(1) =3a(2) =6a(3) =4a(4) =10a(5) =13a(6) =22a(7) =30a(8) =41a(9) =55a(10) =72a(11) =92a(12) =118a(13) =201a(14) =255a(15) =310a(16) =377a(17) =451a(18) =532a(19) =820a(20) =946a(21) =1081a(22) =1225a(23) =1728a(24) =1930a(25) =2159a(26) =2384a(27) =3142a(28) =3456a(29) =3785