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%I #8 Mar 28 2023 13:59:51
%S 28,55,528,255255,525825,828828,22528828,58855825,88252255,285258555,
%T 252852582885,255285258288528,255828252825225,825882525828828,
%U 255888285855228855,555888585855288828885,55255285258252252552225,282882828558888582552522225,528225588525528822525588858528585
%N Triangular numbers composed of digits {2,5,8}.
%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr258.html">Tridigital Triangular Numbers</a>.
%F a(n) = A000217(A119169(n)). - _Tyler Busby_, Mar 28 2023
%Y Cf. A000217, A053927, A119169. See A119033 for a table of cross-references.
%K nonn,base
%O 1,1
%A _Giovanni Resta_, May 10 2006
%E a(18)-a(19) from _Tyler Busby_, Mar 28 2023