%I #10 Mar 26 2023 06:04:09
%S 3,45,55,435,34453,455535,3355345,3544453,45453345,334434453,
%T 355444453,3433345545,4544333445,5435334453,35554444453,44555453355,
%U 3555544444453,53443433535355,355555444444453,454555345444453,5355435453444453,35455445544444555
%N Triangular numbers composed of digits {3,4,5}.
%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr345.html">Tridigital Triangular Numbers</a>
%F a(n) = A000217(A119183(n)).
%Y Cf. A000217, A053937, A119183. See A119033 for a table of cross-references.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, May 10 2006
%E a(21)-a(22) from _Tyler Busby_, Mar 24 2023