Numbers k such that the k-th triangular number contains only digits {0,1,3}.

Terms

a(0) =1a(1) =2a(2) =4a(3) =24a(4) =77a(5) =141a(6) =778a(7) =1421a(8) =1435a(9) =1620a(10) =14220a(11) =15035a(12) =45453a(13) =148533a(14) =148546a(15) =249122a(16) =471404a(17) =791597a(18) =4497399a(19) =2580747997a(20) =47180737658a(21) =148411814220a(22) =244989930458a(23) =447283652733