Numbers k such that the k-th triangular number contains only digits {3,4,5}.

Terms

a(0) =2a(1) =9a(2) =10a(3) =29a(4) =262a(5) =954a(6) =2590a(7) =2662a(8) =9534a(9) =25862a(10) =26662a(11) =82865a(12) =95334a(13) =104262a(14) =266662a(15) =298514a(16) =2666662a(17) =10338610a(18) =26666662a(19) =30151462a(20) =103493337a(21) =266290989a(22) =266666662a(23) =1043584537a(24) =2666666662a(25) =3302531009a(26) =10531233862a(27) =26288192537