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%I #12 Jan 23 2022 12:46:09
%S 0,4,14,45,143,452,1431,4549,14334,46097
%N Smallest number m needing exactly n distinct digits in decimal representation of m*(m+1)/2.
%C A118668(a(n)) = n and A118668(m) <> n for m < a(n).
%o (Haskell)
%o a255678 n = head $ filter ((== n) . a118668) [0..]
%Y Cf. A118668, A260214 (the resulting triangular numbers).
%K nonn,base,fini,full
%O 1,2
%A _Reinhard Zumkeller_, Jul 11 2015
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