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A248715
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Isolated numbers: Mark the lowest number that doesn't touch a number that has already been mark on grid of number spiraling outward.
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1
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1, 10, 12, 15, 17, 19, 21, 23, 31, 48, 50, 52, 54, 60, 62, 64, 67, 69, 71, 73, 75, 77, 89, 91, 93, 101, 118, 120, 122, 124, 126, 128, 138, 140, 142, 148, 150, 152, 154, 156, 159, 161, 163, 179, 181, 183, 185, 187, 195, 197, 199, 211, 220, 222, 224, 226, 228
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OFFSET
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1,2
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COMMENTS
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Start by creating a grid of integers starting with 1 in the center and spiraling outward.
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64--63--62--61--60--59--58--57
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37--36--35--34--33--32--31 56
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38 17--16--15--14--13 30 55
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39 18 5---4---3 12 29 54
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40 19 6 1---2 11 28 53
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41 20 7---8---9--10 27 52
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42 21--22--23--24--25--26 51
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43--44--45--46--47--48--49--50
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Then starting with 1 mark all numbers that have no neighboring marked numbers.
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. 64 __ 62 __ 60 __ __ __
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. __ __ __ __ __ __ 31 __
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. __ 17 __ 15 __ __ __ __
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. __ __ __ __ __ 12 __ 54
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. __ 19 __ 1 __ __ __ __
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. __ __ __ __ __ 10 __ 52
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. __ 21 __ 23 __ __ __ __
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. __ __ __ __ __ 48 __ 50
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LINKS
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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