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Search: id:A063643
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| A063643 |
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Primes with 2 representations: p*q - 2 = u*v + 2 where p, q, u and v are primes. |
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+0
4
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| 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; listen)
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OFFSET
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1,1
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COMMENT
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Or, primes p such that p+/-2 are semiprimes. - Zak Seidov, Mar 08 2006
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..1000
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EXAMPLE
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A063643(25) = 751: 751 = A063637(60)= 753 - 2 = 3*251 - 2, 751 = A063638(55)= 749 + 2 = 7*107 + 2.
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PROGRAM
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(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)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 26 2009]
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CROSSREFS
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A063637, A063638, A001358.
Cf. A109611 (Chen primes)
Sequence in context: A134797 A153740 A055114 this_sequence A057876 A051362 A034302
Adjacent sequences: A063640 A063641 A063642 this_sequence A063644 A063645 A063646
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 21 2001
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