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%I #18 Mar 30 2023 20:56:09
%S 3,28,3828,828828,388333828828,223832333328828,332828222833288828828,
%T 28388332838238232223328828
%N Triangular numbers composed of digits {2,3,8}.
%C a(9) > 10^45. - _Tyler Busby_, Mar 29 2023
%H Giovanni Resta, <a href="http://www.numbersaplenty.com/tr/tr238.html">Tridigital Triangular Numbers</a>.
%F a(n) = A000217(A119157(n)). - _Tyler Busby_, Mar 29 2023
%o (Python)
%o klimit = 10**6
%o A000217 = (k*(k+1)//2 for k in range(klimit)) # generator
%o print([m for m in A000217 if set(str(m)) <= set("238")]) # _Michael S. Branicky_, Mar 28 2021
%Y Cf. A000217, A119157. See A119033 for a table of cross-references.
%K nonn,base,more
%O 1,1
%A _Giovanni Resta_, May 10 2006
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