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A318700 Positive numbers that contain odd and even digits. 4

%I

%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 100,101,102,103,104,105,106,107,108,109,110,112,114,116,118,120,121,122

%N Positive numbers that contain odd and even digits.

%C The sequence of first differences takes on the values {1, 2, 3} only, and each of these values occurs infinitely often (the values 1 and 2 are clear; for the value 3, note that consecutive numbers such as 199..9, 200..0 and 399..9, 400..0 that are excluded from the sequence occur infinitely often).

%C Numbers n such that A065031(n) is a term of A111066. - _Felix Fröhlich_, Sep 01 2018

%C Nonnegative integers excluding those such that digits in their decimal representation share all the same parity. - _R. J. Cano_, Sep 10 2018

%H R. J. Cano, <a href="/A318700/a318700.txt">PARI program</a>

%e 49 and 50 are in the sequence but 19 and 20 are not.

%t Select[Range@ 122, Union[Mod[IntegerDigits[#], 2]] == {0, 1} &] (* _Michael De Vlieger_, Sep 04 2018 *)

%o (PARI) is(n) = my(d=digits(n), v=[]); if(n < 10, return(0)); for(k=1, #d, v=concat(v, [d[k]%2])); vecmin(v)!=vecmax(v) \\ _Felix Fröhlich_, Sep 01 2018

%o (PARI) See Cano link.

%Y Cf. A065031, A111066, A030141, A054684, A227870.

%K nonn,base,easy

%O 1,1

%A _Enrique Navarrete_, Aug 31 2018

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Last modified May 12 04:27 EDT 2021. Contains 343810 sequences. (Running on oeis4.)