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%I #30 Jun 23 2022 20:32:14
%S 10,12,14,16,18,21,23,25,27,29,30,32,34,36,38,41,43,45,47,49,50,52,54,
%T 56,58,61,63,65,67,69,70,72,74,76,78,81,83,85,87,89,90,92,94,96,98,
%U 1001,1003,1005,1007,1009,1010,1012,1014,1016,1018,1021,1023,1025
%N Numbers with equal number of even and odd digits.
%C Numbers with an odd digit length cannot be in this sequence. - _Alonso del Arte_, Nov 02 2013
%H Amiram Eldar, <a href="/A227870/b227870.txt">Table of n, a(n) for n = 1..10000</a>
%e 1009 has 2 even digits (00) and 2 odd digits (19) and so is in the sequence.
%t Select[Range[1025], (d = Differences[Tally[Mod[IntegerDigits[#], 2]]]) != {} && d[[1, 2]] == 0 &] (* _Amiram Eldar_, Oct 01 2020 *)
%o (JavaScript)
%o for (i = 1; i < 5000; i++) {
%o s = i.toString();
%o odds = 0; evens = 0;
%o for (j = 0; j < s.length; j++) if (s.charAt(j)%2 == 0) evens++; else odds++;
%o if (odds == evens) document.write(i + ", ");
%o }
%o (PARI) isok(m) = my(d=digits(m)); #select(x->(x%2), d) == #select(x->!(x%2), d); \\ _Michel Marcus_, Oct 01 2020
%o (Python)
%o def ok(i):
%o stri = str(i)
%o se = sum(1 for d in stri if d in "02468")
%o so = sum(1 for d in stri if d in "13579")
%o return se == so
%o def aupto(nn):
%o alst, an = [None], 0
%o for n in range(1, nn+1):
%o while len(alst) < nn+1:
%o if ok(an): alst.append(an)
%o an += 1
%o return alst[1:] # use alst[n] for a(n)
%o print(aupto(58)) # _Michael S. Branicky_, Dec 14 2020
%Y Cf. A030141, A031443.
%K nonn,base,easy
%O 1,1
%A _Jon Perry_, Nov 02 2013
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