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%I #12 Feb 02 2019 18:46:54
%S 3,4,7,8,16,23,49,89,331,497,1122,11222
%N Numbers k such that 2^prime(k) - prime(k)^2 is prime.
%C No more terms below 5000. - _Giovanni Resta_, Apr 03 2006
%C p is a prime element of the sequence A072180 iff pi(p) is a term of A117587. So since 119087 is a prime term of A072180, pi(119087)= 11222 is in the sequence. - _Farideh Firoozbakht_, Dec 08 2006
%e 4 is in the sequence because the 4th prime is 7 and 2^7 - 7^2 = 79 is a prime.
%p a:=proc(n) if isprime(2^ithprime(n)-ithprime(n)^2) then n else fi end: seq(a(n),n=1..400); # _Emeric Deutsch_, Apr 06 2006
%t Select[Range[1200], PrimeQ[2^# - #^2] &@ Prime@ # &] (* _Michael De Vlieger_, Feb 02 2019 *)
%o (PARI) for(i=1,100,if(isprime(2^prime(i)-prime(i)^2),print1(i,",")))
%Y Cf. A072180.
%K hard,more,nonn
%O 1,1
%A Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Apr 03 2006
%E 3 more terms from _Giovanni Resta_, Apr 03 2006
%E One more term from _Farideh Firoozbakht_, Dec 08 2006
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