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Search: id:A080863
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| A080863 |
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Numbers n such that spf(n)-2 = spf(n+2), where spf=A020639 (smallest prime factor). |
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2
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| 25, 55, 85, 115, 145, 175, 203, 205, 235, 265, 295, 325, 355, 385, 413, 415, 445, 475, 505, 535, 565, 595, 623, 625, 655, 685, 715, 745, 775, 805, 833, 835, 865, 895, 925, 955, 985, 1015, 1043, 1045, 1075, 1105, 1135, 1165, 1195, 1225, 1253, 1255, 1285
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OFFSET
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1,1
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COMMENT
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(spf(n+2),spf(n)) are twin prime pairs.
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EXAMPLE
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16151=31*521, 16151+2=16153=29*557, and (29,31)=(A001359(5), A006512(5)), therefore 16151 is a term: a(625)=16151, A080864(625)=16153.
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CROSSREFS
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Cf. A080864(n)=a(n)+2, A001359, A006512.
Sequence in context: A117472 A123825 A108166 this_sequence A091214 A036305 A125827
Adjacent sequences: A080860 A080861 A080862 this_sequence A080864 A080865 A080866
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 21 2003
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