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A164898 First differences of numbers having only odd digits in their decimal representation.

%I A164898 #7 Jan 24 2022 16:04:25
%S A164898 2,2,2,2,2,2,2,2,2,12,2,2,2,2,12,2,2,2,2,12,2,2,2,2,12,2,2,2,2,12,2,2,
%T A164898 2,2,12,2,2,2,2,12,2,2,2,2,12,2,2,2,2,12,2,2,2,2,112,2,2,2,2,12,2,2,2,
%U A164898 2,12,2,2,2,2,12,2,2,2,2,12,2,2,2,2,112,2,2,2,2,12,2,2,2,2,12,2,2,2,2,12
%N A164898 First differences of numbers having only odd digits in their decimal representation.
%C A164898 a(n) = A014261(n+1) - A014261(n);
%C A164898 all terms are of the form (10^k + 8)/9, see A047855;
%C A164898 a(n) > 2 iff A014261(n) mod 10 = 9.
%H A164898 Robert Israel, <a href="/A164898/b164898.txt">Table of n, a(n) for n = 1..10000</a>
%p A164898 R[1]:= [1,3,5,7,9]:
%p A164898 for d from 2 to 3 do
%p A164898   R[d]:= map(t -> seq(10*t+i,i=[1,3,5,7,9]),R[d-1])
%p A164898 od:
%p A164898 B:= map(op,[seq(R[d],d=1..3)]):
%p A164898 B[2..-1]-B[1..-2]; # _Robert Israel_, Jan 24 2022
%t A164898 Differences[Select[Range[1000],Count[IntegerDigits[#],_?EvenQ]==0&]] (* _Harvey P. Dale_, Jan 03 2019 *)
%Y A164898 Cf. A014261.
%K A164898 nonn,base
%O A164898 1,1
%A A164898 _Reinhard Zumkeller_, Aug 30 2009