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A108183
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Primes equal to the sum of two successive semiprimes.
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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; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| 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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LINKS
| Moshe Levin, Table of n, a(n) for n = 1..10000
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EXAMPLE
| 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
| 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
| Cf. A109404.
Sequence in context: A133765 A158846 A157026 * A157483 A173966 A096218
Adjacent sequences: A108180 A108181 A108182 * A108184 A108185 A108186
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KEYWORD
| easy,nonn
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AUTHOR
| Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Jun 14 2005
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EXTENSIONS
| 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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