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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-Fran├žois 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.)