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Search: id:A068088
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| A068088 |
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n-3, n-2, n-1, n+1, n+2 and n+3 are squarefree. |
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1
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| 4, 32, 36, 40, 68, 104, 108, 112, 140, 180, 184, 212, 216, 220, 256, 284, 320, 356, 392, 396, 400, 432, 436, 464, 468, 500, 544, 612, 616, 644, 680, 716, 756, 760, 788, 792, 796, 860, 896, 900, 904, 936, 940, 968, 1004, 1008, 1040, 1044, 1112, 1116, 1120, 1156, 1188, 1192, 1220, 1256, 1260, 1264
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OFFSET
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0,1
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COMMENT
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There can not be four consecutive square-free numbers as one of them is divisible by 2^2 =4.
From 28 to 44 there are 12 square-free numbers among 15 consecutive integers. Other examples are 100 to 116 and 212 to 228.
The largest possible run of consecutive multiples of 4 in the sequence is 3: If n, n+4 and n+8 are in the sequence then n+4 and hence n-5 and n+13 must be divisible by 9, so neither n-4 nor n+12 can be in the sequence. - Ulrich Schimke, Apr 13, 2002
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EXAMPLE
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36 is a term as 33,34,35 and 37,38,39 are two sets of three consecutive square-free numbers.
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CROSSREFS
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Cf. A007675, A039833.
Adjacent sequences: A068085 A068086 A068087 this_sequence A068089 A068090 A068091
Sequence in context: A084764 A061789 A103909 this_sequence A118901 A114076 A078092
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KEYWORD
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easy,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 18 2002
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EXTENSIONS
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Corrected and extended by Ulrich Schimke, Apr 13, 2002. Further correction from Harvey P. Dale (hpd1(AT)nyu.edu), May 01 2002.
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