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A109953
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Primes p such that p^2+2 is a semiprime.
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7
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2, 7, 11, 17, 29, 37, 43, 53, 73, 79, 83, 97, 137, 191, 233, 251, 263, 269, 271, 277, 281, 359, 379, 389, 433, 461, 479, 521, 541, 577, 601, 631, 647, 677, 691, 719, 739, 827, 829, 863, 881, 929, 947, 983, 997, 1033, 1063, 1087, 1109, 1187, 1223
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Cf. A048161 Primes p such that p^2+1 is a semiprime.
Primes p such that (p^2+2)/3 is prime. For all primes q>3, we have q=6k+-1 for some k, which makes it easy to show that 3 divides q^2+2. Hence if q^2+2 is a semiprime then (q^2+2)/3 must be prime. - T. D. Noe (noe(AT)sspectra.com), May 05 2006
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LINKS
| Harvey P. Dale, Table of n, a(n) for n = 1..2500
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EXAMPLE
| 7 is ok because 7^2+2=51=3*17 (semiprime).
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MATHEMATICA
| A109953=Select[Prime[Range[200]], Plus@@Last/@FactorInteger[ #^2+2]==2&]
Select[Prime[Range[200]], PrimeOmega[#^2+2]==2&] (* From Harvey P. Dale, Nov 19 2011 *)
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CROSSREFS
| Cf. A048161.
Cf. A118915 (primes p such that (p^2+5)/6 is prime).
Sequence in context: A019385 A075552 A124854 * A165810 A109417 A174360
Adjacent sequences: A109950 A109951 A109952 * A109954 A109955 A109956
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KEYWORD
| nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Jul 06 2005
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