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A160844
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Number of lines through at least 2 points of an 4 X n grid of points
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0
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0, 1, 18, 35, 62, 93, 136, 181, 238, 299, 370, 445, 532, 621, 722, 827, 942, 1061, 1192, 1325, 1470, 1619, 1778, 1941, 2116, 2293, 2482, 2675, 2878, 3085, 3304, 3525, 3758, 3995, 4242, 4493, 4756, 5021, 5298, 5579, 5870, 6165, 6472, 6781, 7102, 7427, 7762
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| S. Mustonen, On lines and their intersection points in a rectangular grid of points
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FORMULA
| a(n)=2*a(n-1)-a(n-2)+C(mod(n+2,6)+1)), C=(10,4,12,2,12,4)
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MATHEMATICA
| a[0]=0; a[1]=1; a[2]=18; a[3]=35; a[n_]:=a[n]=a[n]=2*a[n-1]-a[n-2]+R[n] c4={10, 4, 12, 2, 12, 4}; R[n_]:=c4[[Mod[n+2, 6]+1]] Table[a[n], {n, 0, 46}]
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CROSSREFS
| Sequence in context: A044063 A044444 A014640 * A040306 A073332 A109428
Adjacent sequences: A160841 A160842 A160843 * A160845 A160846 A160847
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KEYWORD
| nonn
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AUTHOR
| Seppo Mustonen (seppo.mustonen(AT)helsinki.fi), May 28 2009
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