A344170 Numbers k such that 3^(2*k+1) - 3^k - 1 is prime.
1, 2, 5, 6, 7, 10, 17, 25, 31, 88, 95, 137, 141, 416, 610, 781, 800, 2353, 7291, 9627, 9749, 15946, 19215
Offset: 1
Crossrefs
Cf. A344263.
Programs
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Maple
for k from 1 to 3000 do if isprime(3^(2*k + 1) - 3^k - 1) then print(k); end if; end do
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Mathematica
Do[If[PrimeQ[3^(2k + 1) - 3^k - 1], Print[k]], {k, 1, 3000}] -
PARI
for(k=1, 3e3, if(isprime(3^(2*k+1)-3^k-1), print1(k", ")))
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SageMath
for k in range(1, 3000): if is_prime(3^(2 * k + 1) - 3^k - 1): print(k)
Extensions
a(19)-a(21) from Michael S. Branicky, May 11 2021
a(22)-a(23) from Reza K Ghazi, May 14 2021
Comments