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A280824 Numbers with an even number of digits and with an even number of distinct digits.

%I A280824 #15 Feb 16 2025 08:33:39
%S A280824 10,12,13,14,15,16,17,18,19,20,21,23,24,25,26,27,28,29,30,31,32,34,35,
%T A280824 36,37,38,39,40,41,42,43,45,46,47,48,49,50,51,52,53,54,56,57,58,59,60,
%U A280824 61,62,63,64,65,67,68,69,70,71,72,73,74,75,76,78,79,80,81,82,83,84,85,86,87,89,90,91,92,93,94,95,96,97,98,1000,1001,1010
%N A280824 Numbers with an even number of digits and with an even number of distinct digits.
%C A280824 Differs from A139819 (the latter contains 100, for example). - _R. J. Mathar_, Jan 17 2017
%H A280824 Michael S. Branicky, <a href="/A280824/b280824.txt">Table of n, a(n) for n = 1..10000</a>
%H A280824 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Digit.html">Digit</a>
%H A280824 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%F A280824 A000035(A055642(a(n))) = 0.
%F A280824 A000035(A043537(a(n))) = 0.
%F A280824 a(n) = A029742(n) for n < 82.
%p A280824 isA280824 := proc(n)
%p A280824     if n < 10 then
%p A280824         return false;
%p A280824     end if;
%p A280824     dgs := convert(n,base,10) ;
%p A280824     if type(nops(dgs),'even') then
%p A280824         type(nops(convert(dgs,set)),'even') ;
%p A280824     else
%p A280824         false;
%p A280824     end if;
%p A280824 end proc: # _R. J. Mathar_, Jan 17 2017
%t A280824 Select[Range[1010], Mod[Length[IntegerDigits[#1]], 2] == 0 && Mod[Length[Union[IntegerDigits[#1]]], 2] == 0 & ]
%o A280824 (Python)
%o A280824 def ok(n): s = str(n); return len(s)%2 == 0 == len(set(s))%2
%o A280824 print(list(filter(ok, range(1011)))) # _Michael S. Branicky_, Oct 12 2021
%Y A280824 Cf. A000035, A001637, A029742, A043537, A055642, A280823, A280825, A280826.
%K A280824 nonn,base,easy
%O A280824 1,1
%A A280824 _Ilya Gutkovskiy_, Jan 08 2017