A375214 Odd numbers with equal numbers of even and odd digits.

21, 23, 25, 27, 29, 41, 43, 45, 47, 49, 61, 63, 65, 67, 69, 81, 83, 85, 87, 89, 1001, 1003, 1005, 1007, 1009, 1021, 1023, 1025, 1027, 1029, 1041, 1043, 1045, 1047, 1049, 1061, 1063, 1065, 1067, 1069, 1081, 1083, 1085, 1087, 1089, 1201, 1203, 1205, 1207, 1209, 1221, 1223, 1225

Offset

1,1

Comments

Numbers with an odd length cannot be in this sequence.

Links

Jake L Lande, Table of n, a(n) for n = 1..1000

Example

1001 is odd and has two even digits (0,0) and two odd digits (1,1).

Maple

filter:= proc(n) local L;
  L:= convert(n, base, 10);
  nops(select(type, L, even))=nops(L)/2
end proc:
select(filter, [seq(seq(i, i=10^(d-1)+1 .. 10^d, 2), d=2..4, 2)]); # Robert Israel, Aug 07 2024

Mathematica

eeo[n_] := (id = IntegerDigits[n]; Count[EvenQ@id, True] == Count[OddQ@id, True]); Select[Select[Range[1225], eeo], Mod[#, 2] == 1 &]

Crossrefs

Subsequence of A227870.

Complement of A375213 within A227870.

Sequence in context: A007929 A143712 A163396 * A169903 A095447 A095443

Adjacent sequences: A375209 A375212 A375213 * A375218 A375219 A375220

Keyword

nonn,base,easy

Author

Jake L Lande, Aug 07 2024

Status

approved