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A020755
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Increasing gaps between squarefree numbers (upper end).
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4
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2, 5, 10, 51, 246, 849, 22026, 217077, 1092755, 8870033, 221167433, 47255689927, 82462576233, 1043460553378, 79180770078563, 3215226335143234, 23742453640900989, 125781000834058586
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OFFSET
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1,1
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COMMENTS
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Up to n=10, a(n) is the upper end of the first gap of length n. However, for n=11 through n=16, a(n) is the upper end of the first gap of length n+1. See A020753. - M. F. Hasler, Dec 28 2015
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LINKS
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FORMULA
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EXAMPLE
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The first gap in A005117 occurs between 1 and 2 and has length 1. The next largest gap occurs between 3 and 5 and has length 2. The next largest gap is between 7 and 10 and has length 3. Etc. We are only interested in gaps that set new records.
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PROG
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(PARI) A020755(n)=for(k=L=1, 9e9, issquarefree(k)||next; k-L>=n&&return(k); L=k) \\ M. F. Hasler, Dec 28 2015
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CROSSREFS
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KEYWORD
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nonn,hard
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AUTHOR
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EXTENSIONS
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Thanks to Christian Bower for additional comments.
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STATUS
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approved
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