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Search: id:A052214
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| A052214 |
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Numbers n with prime signature(n) = prime signature(n+1) = prime signature(n+2). |
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+0
3
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| 33, 85, 93, 141, 201, 213, 217, 301, 393, 445, 603, 633, 697, 921, 1041, 1137, 1261, 1274, 1309, 1345, 1401, 1641, 1761, 1837, 1885, 1893, 1924, 1941, 1981, 2013, 2101, 2181, 2217, 2305, 2361, 2433, 2461, 2517, 2523, 2641, 2665, 2721, 2733, 3097, 3385
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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pri[ n_ ] := Sort[ Transpose[ FactorInteger[ n ] ][ [ 2 ] ] ] Select[ Range[ 2,10000 ],pri[ # ]==pri[ #+1 ]==pri[ #+2 ]& ]
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EXAMPLE
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33 = 3^1 11^1, 34 = 2^1 17^1, and 35 = 5^1 7^1, so all have prime signature {1,1,1}.
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CROSSREFS
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Cf. A075039.
Sequence in context: A056809 A073251 A005238 this_sequence A063838 A075039 A039833
Adjacent sequences: A052211 A052212 A052213 this_sequence A052215 A052216 A052217
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KEYWORD
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easy,nonn
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AUTHOR
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Erich Friedman (efriedma(AT)stetson.edu), Jan 29 2000
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