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A064402
Numbers n such that prime(n)+n is a prime, where prime(n) denotes the n-th prime number.
19
1, 2, 4, 6, 18, 22, 24, 26, 32, 34, 42, 48, 66, 70, 72, 82, 92, 96, 98, 100, 102, 104, 106, 108, 114, 116, 126, 130, 144, 150, 152, 158, 172, 180, 200, 202, 204, 206, 218, 222, 228, 236, 270, 282, 290, 300, 312, 322, 324, 328, 330, 350, 352, 356, 362, 378, 384
OFFSET
1,2
COMMENTS
a(n) = order among the primes of A061067(n).
Except for the first one all terms are even. Conjecture: First differences include all even integers. - Zak Seidov, Nov 10 2013
LINKS
FORMULA
a(n) = A061068(n) - A061067(n-1).
A014688(a(n)) = A061068(n). - Zak Seidov, Nov 10 2013
MATHEMATICA
Select[ Range[ 400 ], PrimeQ[ Prime[ # ] + # ] & ]
PROG
(PARI) { n=0; for (m=1, 10^9, if (isprime(prime(m) + m), write("b064402.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 13 2009
(Magma) [n: n in [0..500]| IsPrime(NthPrime(n) +n)]; // Vincenzo Librandi, Apr 06 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Sep 28 2001
EXTENSIONS
Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 08 2007
STATUS
approved