A178996 Numbers n such that 5^n mod 2^n is prime.
3, 10, 19, 24, 28, 61, 79, 96, 104, 125, 132, 191, 196, 243, 292, 302, 462, 466, 586, 621, 1508, 3307, 3823, 4729, 5370, 6721, 8110, 11145, 13502, 13762, 20266, 27868, 38522, 75470
Offset: 1
Crossrefs
Cf. A178995.
Programs
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Mathematica
fQ[n_] := PrimeQ@ PowerMod[5, n, 2^n]; k = 1; lst = {}; While[k < 17501, If[fQ@ k, AppendTo[lst, k]]; k++]; lst -
PARI
for(n=1,9999, ispseudoprime(5^n % 2^n) & print1(n",")) \\ M. F. Hasler, Jan 03 2011
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PARI
for(n=1,1e5,if(ispseudoprime(lift(Mod(5,2^n)^n)),print1(n", "))) \\ Charles R Greathouse IV, Oct 10 2011
Extensions
a(31)-a(34) from Charles R Greathouse IV, Oct 10 2011
Comments