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Search: id:A119718
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| A119718 |
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A permutation of semiprimes: every term is relatively prime to its neighbors. |
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+0
1
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| 4, 9, 10, 21, 22, 15, 14, 25, 6, 35, 26, 33, 34, 39, 38, 49, 46, 51, 55, 57, 58, 65, 62, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95, 106, 111, 115, 118, 119, 121, 122, 123, 133, 129, 134, 141, 142, 143, 145, 146, 155, 158, 159, 161, 166, 169, 177, 178, 183, 185, 187
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is highly probable that the sequence is a permutation of the semiprimes.
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MATHEMATICA
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sp0=Select[Range[1000], 2==Plus@@Last/@FactorInteger@#&]; sp=sp0; le=Length@sp; seq={4}; b=4; sp=Rest@sp; le=le-1; Do[Do[spi=sp[[i]]; If[1==GCD[b, spi], b=spi; AppendTo[seq, b]; sp=Delete[sp, i]; le=le-1; Break[]], {i, le}], {100}]; seq
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CROSSREFS
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Sequence in context: A155566 A102837 A004631 this_sequence A051884 A131368 A131457
Adjacent sequences: A119715 A119716 A119717 this_sequence A119719 A119720 A119721
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Jun 13 2006
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