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%I #23 Mar 01 2023 09:08:54
%S 0,3,4,11,35,56,88,104,476,1367,1707,2472,22232,25260
%N Numbers m such that 3^(2m+1) - 3^m + 1 is prime.
%C a(14) > 30000.
%p for m from 0 to 3000 do if isprime(3^(2*m + 1) - 3^m + 1) then print(m); end if; end do;
%t Do[If[PrimeQ[3^(2 m + 1) - 3^m + 1], Print[m]], {m, 0, 3000}]
%t Select[Range[0,2500],PrimeQ[3^(2#+1)-3^#+1]&] (* _Harvey P. Dale_, Mar 01 2023 *)
%o (PARI) for(m=0, 3e3, if(isprime(3^(2*m+1)-3^m+1), print1(m", ")))
%o (SageMath)
%o for m in range(3000):
%o if is_prime(3^(2*m + 1) - 3^m + 1):
%o print(m)
%Y Cf. A344170.
%K nonn,more
%O 1,2
%A _Reza K Ghazi_, May 13 2021
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