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%I #41 Dec 04 2019 11:17:44
%S 3,17,41,67,83,109,157,191,211,241,283,353,367,401,461,509,547,563,
%T 587,617,739,773,797,859,877,967,991,1031,1087,1171,1201,1217,1409,
%U 1433,1447,1471,1499,1597,1621,1669,1723,1741,1823,1913,2027,2063,2081,2099
%N Primes prime(k) for which A049076(k) = 2.
%H Charles R Greathouse IV, <a href="/A049078/b049078.txt">Table of n, a(n) for n = 1..10000</a>
%H N. Fernandez, <a href="http://www.borve.org/primeness/FOP.html">An order of primeness, F(p)</a>
%H N. Fernandez, <a href="/A006450/a006450.html">An order of primeness</a> [cached copy, included with permission of the author]
%F a(n) = prime(A007821(n)). - _Juri-Stepan Gerasimov_, Aug 11 2008
%F a(n) ~ A006450(n) ~ n log^2 n. - _Charles R Greathouse IV_, Apr 29 2015
%e For these primes S(p) is a prime but S(S(p)) is not. E.g. S(17)=7, S(7)=4.
%p A049078 := proc(n) ithprime(A007821(n)) ; end proc: # _R. J. Mathar_, Aug 14 2008
%t Nest[ Prime, Select[ Range[70], !PrimeQ[ # ] &], 2] (* _Robert G. Wilson v_, Mar 15 2004 *)
%o (PARI) is(n)=my(p=primepi(n)); isprime(p) && !isprime(primepi(p)) && isprime(n) \\ _Charles R Greathouse IV_, Apr 29 2015
%Y Cf. A049076, A007821, A049079-A049081, A058322, A058324-A058328, A093046, A006450, A018252, A236542.
%Y Let A = primes A000040, B = nonprimes A018252. The 2-level compounds are AA = A006450, AB = A007821, BA = A078782, BB = A102615. The 3-level compounds AAA, AAB, ..., BBB are A038580, A049078, A270792, A102617, A270794, A270795, A270796, A102616.
%K nonn
%O 1,1
%A _Neil Fernandez_
%E Edited by _N. J. A. Sloane_, Aug 29 2008 at the suggestion of _R. J. Mathar_
%E Spelling/notation corrections by _Charles R Greathouse IV_, Mar 18 2010
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