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A244210 First differences of A244209. 1

%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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Last modified March 29 10:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)