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A109805
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a(n) = prime(n+2)*prime(n+1) - prime(n)*prime(n+1).
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1
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9, 20, 42, 66, 78, 102, 114, 230, 232, 248, 370, 246, 258, 470, 636, 472, 488, 670, 426, 584, 790, 830, 1246, 1164, 606, 618, 642, 654, 2034, 2286, 1310, 1096, 1668, 1788, 1208, 1884, 1630, 1670, 2076, 1432, 2172, 2292, 1158, 1182, 2786, 5064, 3568, 1362
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 9 is the only semiprime of the form prime(n+2)*prime(n+1) - prime(n)*prime(n+1).
First differences of A006094. [Reinhard Zumkeller, Mar 13 2011]
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MATHEMATICA
| Table[Prime[n + 1]*(Prime[n + 2] - Prime[n]), {n, 48}] (*Chandler*)
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CROSSREFS
| The largest prime factor of a(n) gives the sequence A000040.
Sequence in context: A146680 A143704 A128153 * A013573 A146388 A013338
Adjacent sequences: A109802 A109803 A109804 * A109806 A109807 A109808
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KEYWORD
| easy,nonn
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AUTHOR
| Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Aug 16 2005
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EXTENSIONS
| Edited and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Aug 17 2005
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