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%I #10 Mar 25 2016 16:30:30
%S 1,2,5,8,9,15,26,53,63,86,92,93,95,116,137,152,233,254,281,303,329,
%T 334,352,386,392,415,423,460,470,476,508,565,570,601,660,673,680,725,
%U 748,898,907,942,948,952,958,1045,1119,1126,1138,1140,1259,1314,1360
%N 2*prime(prime(prime(n)))-3 and 3*prime(prime(prime(n)))-2 are both primes.
%e a(1) = 1 because 2*p(p(p(1)))-3 = 7 = prime and 3*p(p(p(1)))-2 = 13 = prime;
%e a(2) = 2 because 2*p(p(p(2)))-3 = 19 = prime and 3*p(p(p(2)))-2 = 31 = prime;
%e a(3) = 5 because 2*p(p(p(5)))-3 = 379 = prime and 3*p(p(p(5)))-2 = 251 = prime;
%e a(4) = 8 because 2*p(p(p(8)))-3 = 991 = prime and 3*p(p(p(8)))-2 = 659 = prime;
%e a(5) = 9 because 2*p(p(p(9)))-3 = 1291 = prime and 3*p(p(p(9)))-2 = 859 = prime;
%e a(6) = 15 because 2*p(p(p(15)))-3 = 3889 = prime and 3*p(p(p(15)))-2 = 2591 = prime.
%t pppQ[n_]:=Module[{p=Prime[Prime[Prime[n]]]},AllTrue[{2p-3,3p-2},PrimeQ]]; Select[Range[1400],pppQ] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Mar 25 2016 *)
%o (PARI) isok(n) = isprime(2*prime(prime(prime(n)))-3) && isprime(3*prime(prime(prime(n)))-2); \\ _Michel Marcus_, Sep 02 2013
%Y Cf. A038580, A063908, A088878.
%K nonn
%O 1,2
%A _Juri-Stepan Gerasimov_, Feb 15 2010
%E Extended beyond 15 by _R. J. Mathar_, Mar 01 2010
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