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Search: id:A108183
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| A108183 |
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Primes equal to the sum of two successive semiprimes. |
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+0
1
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| 19, 29, 43, 47, 59, 67, 73, 127, 151, 167, 173, 233, 283, 313, 317, 461, 521, 541, 593, 653, 701, 719, 727, 787, 839, 907, 967, 1249, 1409, 1439, 1471, 1549, 1601, 1831, 1867, 1873, 1913, 1993, 2029, 2083, 2089, 2287, 2311, 2351, 2393, 2579, 2593, 2693
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Primes p such that p = sum of n-th and (n+1)-st semiprimes for some n.
Primes appearing in A109404.
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EXAMPLE
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19 = sp(3) + sp(4) = 9 + 10 where sp(n) = n-th semiprime.
29 is a member because 2*7 + 3*5 = 29.
13 is not a member because although 2*2 + 3*3 = 13, 4 and 9 are not successive semiprimes.
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MATHEMATICA
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Select[ Plus @@@ Partition[ Select[ Range[1250], Plus @@ Last /@ FactorInteger[ # ] == 2 &], 2, 1], PrimeQ[ # ] &] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 14 2005)
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CROSSREFS
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Cf. A109404.
Sequence in context: A133765 A158846 A157026 this_sequence A157483 A096218 A100590
Adjacent sequences: A108180 A108181 A108182 this_sequence A108184 A108185 A108186
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KEYWORD
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easy,nonn
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Jun 14 2005
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EXTENSIONS
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Corrected and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 14 2005
Edited by N. J. A. Sloane (njas(AT)research.att.com), May 03 2007
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