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 A244210 First differences of A244209. 1
 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, -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, 0, 24, -20, 8, 8, 20, -24, 16, 12, -16, 8, 12, -4, 20, -8, 8, -28, 32, 0, -4, -8, 32 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS 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). LINKS Kival Ngaokrajang, Table of n, a(n) for n = 1..1000 PROG (Small Basic) For n=1 to 200   count=0   row=math.Ceiling((n+1)/2)-1     for i=0 To row       for j=0 To row         x=math.power(4*i*i+4*j*j, 1/2)         c1=-x+1-n         c2=-x-1+n         c3=-x+1+n         c4=x+1+n         If x>0 and c1*c2*c3*c4>0 then           c=(1/x)*math.Power(c1*c2*c3*c4, 1/2)         Else           c=0         EndIf         If c>0 Then           count=count+1         EndIf       EndFor     EndFor   If Math.Remainder(n, 2)=0 Then     circle[n]=4*(count-2)+4   Else     circle[n]=4*count   EndIf   If n > 1 Then     TextWindow.Write(circle[n]-circle[n-1]+", ")   EndIf EndFor CROSSREFS Cf. A244209. Sequence in context: A254246 A254375 A019684 * A019867 A144663 A197260 Adjacent sequences:  A244207 A244208 A244209 * A244211 A244212 A244213 KEYWORD sign AUTHOR Kival Ngaokrajang, Jun 22 2014 STATUS approved

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Last modified January 22 04:27 EST 2020. Contains 331133 sequences. (Running on oeis4.)