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Triangular numbers composed of digits {3,4,5}.
2

%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