A370663 Numbers k such that (9^k + 9*k)/9 is prime.
1, 2, 4, 8, 10, 28, 1348, 1424, 12838
Offset: 1
Programs
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Magma
[n: n in [1..130] |IsPrime ((9^n + 9*n) div 9)]; // Vincenzo Librandi, Jul 04 2025
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Mathematica
Select[Range[1,13000],PrimeQ[((9^#+9*#) / 9)]&] (* Vincenzo Librandi, Jul 04 2025 *)
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PARI
is(n) = ispseudoprime(9^(n-1)+n)
Comments