%I #21 Feb 27 2018 16:30:02
%S 8,-4,8,0,4,0,16,-12,8,0,12,-8,8,4,4,4,16,-16,4,0,16,-12,8,8,12,-8,8,
%T -4,0,0,28,-20,20,-8,8,4,0,0,-4,0,32,-4,0,-8,12,-8,8,4,20,-20,16,0,-4,
%U 0,24,-20,8,8,20,-24,16,12,-16,8,12,-4,20,-8,8,-28,32,0,-4,-8,32
%N First differences of A244209.
%C All terms are even with some numbers missing, e.g., 2, 6, 10, 14, 18, 22, 26, 30, ... ,. For the first 1000 terms, the maximum is 136 at a(881) and the minimum is -156 at a(814).
%H Kival Ngaokrajang, <a href="/A244210/b244210.txt">Table of n, a(n) for n = 1..1000</a>
%o (Small Basic)
%o For n=1 to 200
%o count=0
%o row=math.Ceiling((n+1)/2)-1
%o for i=0 To row
%o for j=0 To row
%o x=math.power(4*i*i+4*j*j,1/2)
%o c1=-x+1-n
%o c2=-x-1+n
%o c3=-x+1+n
%o c4=x+1+n
%o If x>0 and c1*c2*c3*c4>0 then
%o c=(1/x)*math.Power(c1*c2*c3*c4,1/2)
%o Else
%o c=0
%o EndIf
%o If c>0 Then
%o count=count+1
%o EndIf
%o EndFor
%o EndFor
%o If Math.Remainder(n,2)=0 Then
%o circle[n]=4*(count-2)+4
%o Else
%o circle[n]=4*count
%o EndIf
%o If n > 1 Then
%o TextWindow.Write(circle[n]-circle[n-1]+", ")
%o EndIf
%o EndFor
%Y Cf. A244209.
%K sign
%O 1,1
%A _Kival Ngaokrajang_, Jun 22 2014
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