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 A063643 Primes with 2 representations: p*q - 2 = u*v + 2 where p, q, u and v are primes. 11
 23, 37, 53, 67, 89, 113, 131, 157, 211, 251, 293, 307, 337, 379, 409, 449, 487, 491, 499, 503, 631, 683, 701, 719, 751, 769, 787, 919, 941, 953, 991, 1009, 1039, 1117, 1193, 1201, 1259, 1381, 1399, 1439, 1459, 1471, 1499, 1511, 1567, 1709, 1733, 1759 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Or, primes p such that p+/-2 are semiprimes. - Zak Seidov, Mar 08 2006 LINKS T. D. Noe, Table of n, a(n) for n=1..1000 FORMULA Intersection of A063637 and A063638. - Zak Seidov, Mar 14 2011 EXAMPLE A063643(25) = 751: 751 = A063637(60)= 753 - 2 = 3*251 - 2, 751 = A063638(55)= 749 + 2 = 7*107 + 2. MATHEMATICA Select[Prime[Range[300]], PrimeOmega[#+2] == PrimeOmega[#-2] == 2&] (* Jean-François Alcover, Mar 02 2019 *) PROG (PARI) { n=0; for (m=2, 10^9, p=prime(m); if (bigomega(p + 2) == 2 && bigomega(p - 2) == 2, write("b063643.txt", n++, " ", p); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 26 2009 CROSSREFS Cf. A063637, A063638, A001358. Cf. A109611 (Chen primes). Sequence in context: A153740 A055114 A268343 * A057876 A244282 A051362 Adjacent sequences:  A063640 A063641 A063642 * A063644 A063645 A063646 KEYWORD nonn AUTHOR Reinhard Zumkeller, Jul 21 2001 STATUS approved

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Last modified July 17 18:47 EDT 2019. Contains 325109 sequences. (Running on oeis4.)