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A101594 Numbers with exactly two distinct decimal digits, neither of which is 0.

%I A101594 #25 May 06 2024 08:05:07
%S A101594 12,13,14,15,16,17,18,19,21,23,24,25,26,27,28,29,31,32,34,35,36,37,38,
%T A101594 39,41,42,43,45,46,47,48,49,51,52,53,54,56,57,58,59,61,62,63,64,65,67,
%U A101594 68,69,71,72,73,74,75,76,78,79,81,82,83,84,85,86,87,89,91,92,93,94,95,96,97,98,112,113,114,115,116,117,118,119,121,122,131
%N A101594 Numbers with exactly two distinct decimal digits, neither of which is 0.
%C A101594 First differs from A125290 at a(83) = 131 != 123 = A101594(83). - _Michael S. Branicky_, Dec 13 2021
%H A101594 Reinhard Zumkeller, <a href="/A101594/b101594.txt">Table of n, a(n) for n = 1..10000</a>
%H A101594 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%F A101594 A168046(a(n)) * A043537(A004719(a(n))) = 2. - _Reinhard Zumkeller_, Jun 18 2013
%t A101594 Select[Range[200], FreeQ[#, 0] && Length[Union[#]] == 2 & [IntegerDigits[#]] &] (* _Paolo Xausa_, May 06 2024 *)
%o A101594 (Haskell)
%o A101594 a101594 n = a101594_list !! (n-1)
%o A101594 a101594_list = filter ((== 2) . a043537) a052382_list
%o A101594 -- _Reinhard Zumkeller_, Jun 18 2013
%o A101594 (Python)
%o A101594 def ok(n): s = set(str(n)); return len(s) == 2 and "0" not in s
%o A101594 print([k for k in range(132) if ok(k)]) # _Michael S. Branicky_, Dec 13 2021
%Y A101594 Cf. A083985, A031955, A004719, A043537, A168046.
%Y A101594 Subsequence of A052382, A125290.
%K A101594 base,easy,nonn,less,look
%O A101594 1,1
%A A101594 _David Wasserman_, Dec 07 2004