Describe the n-th triangular number A000217(n).

Terms

a(0) =10a(1) =11a(2) =13a(3) =16a(4) =1110a(5) =1115a(6) =1211a(7) =1218a(8) =1316a(9) =1415a(10) =25a(11) =26a(12) =1718a(13) =1911a(14) =111015a(15) =111210a(16) =111316a(17) =111513a(18) =111711a(19) =111910a(20) =121110a(21) =121311a(22) =121513a(23) =121716a(24) =1320a(25) =131215a(26) =131511a(27) =131718a(28) =141016a(29) =141315