Vertical of triangular spiral in A051682.

Terms

a(0) =1a(1) =13a(2) =34a(3) =64a(4) =103a(5) =151a(6) =208a(7) =274a(8) =349a(9) =433a(10) =526a(11) =628a(12) =739a(13) =859a(14) =988a(15) =1126a(16) =1273a(17) =1429a(18) =1594a(19) =1768a(20) =1951a(21) =2143a(22) =2344a(23) =2554a(24) =2773a(25) =3001a(26) =3238a(27) =3484a(28) =3739a(29) =4003