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Triangular numbers composed of digits {0,4,5}.
2

%I #14 Mar 15 2023 07:53:30

%S 45,55,4005,5050,404550,405450,500500,40405555,40504500,50005000,

%T 454044045,500054500,4050045000,4540044405,5000050000,405000450000,

%U 455005054540,500000500000,40500004500000,50000005000000,50450455004040,540550504445050,4050000045000000

%N Triangular numbers composed of digits {0,4,5}.

%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr045.html">Tridigital Triangular Numbers</a>

%F a(n) = A000217(A119072(n)). - _Michel Marcus_, Mar 15 2023

%Y Cf. A000217, A058436, A119072. See A119033 for a table of cross-references.

%K nonn,base

%O 1,1

%A _Giovanni Resta_, May 10 2006

%E a(21)-a(23) from _Tyler Busby_, Mar 14 2023