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A102669 Number of digits >= 2 in decimal representation of n.

%I A102669 #28 Feb 19 2023 15:47:58
%S A102669 0,0,1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,1,1,2,2,
%T A102669 2,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,1,1,2,2,2,2,2,2,
%U A102669 2,2,1,1,2,2,2,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,1,1,2,2,2,2,2,2,2,2,0,0,1,1,1
%N A102669 Number of digits >= 2 in decimal representation of n.
%C A102669 a(n) = 0 iff n is in A007088 (numbers in base 2). - _Bernard Schott_, Feb 19 2023
%H A102669 Hieronymus Fischer, <a href="/A102669/b102669.txt">Table of n, a(n) for n = 0..10000</a>
%F A102669 Contribution from _Hieronymus Fischer_, Jun 10 2012: (Start)
%F A102669 a(n) = Sum_{j=1..m+1} (floor(n/10^j + 4/5) - floor(n/10^j)), where m = floor(log_10(n)).
%F A102669 G.f.: g(x) = (1/(1-x))*Sum_{j>=0} (x^(2*10^j) - x^(10*10^j))/(1 - x^10^(j+1)).
%F A102669 General formulas for the number of digits >= d in the decimal representations of n, where 1 <= d <= 9:
%F A102669 a(n) = Sum_{j=1..m+1} (floor(n/10^j + (10-d)/10) - floor(n/10^j)), where m = floor(log_10(n)).
%F A102669 G.f.: g(x) = (1/(1-x))*Sum_{j>=0} (x^(d*10^j) - x^(10*10^j))/(1 - x^10^(j+1)). (End)
%p A102669 p:=proc(n) local b,ct,j: b:=convert(n,base,10): ct:=0: for j from 1 to nops(b) do if b[j]>=2 then ct:=ct+1 else ct:=ct fi od: ct: end: seq(p(n),n=0..116); # _Emeric Deutsch_, Feb 23 2005
%t A102669 Table[Total@ Take[DigitCount@ n, {2, 9}], {n, 0, 104}] (* _Michael De Vlieger_, Aug 17 2017 *)
%Y A102669 Cf. A027868, A054899, A055640, A055641, A102670 - A102685, A117804, A122840, A122841, A160093, A160094, A196563, A196564. Partial sums see A102670.
%Y A102669 Cf. A000120, A000788, A007088, A023416, A059015 (for base 2).
%K A102669 nonn,base,easy
%O A102669 0,23
%A A102669 _N. J. A. Sloane_, Feb 03 2005
%E A102669 More terms from _Emeric Deutsch_, Feb 23 2005