A282943 Numbers k such that 3*2^k + 1 is a prime factor of a generalized Fermat number 7^(2^m) + 1 for some m.
8, 12, 36, 276, 408, 2208, 2816, 3168, 3912, 42665, 44685, 59973, 709968, 916773, 1832496
Offset: 1
Links
- Anders Björn and Hans Riesel, Factors of generalized Fermat numbers, Math. Comp. 67 (1998), no. 221, pp. 441-446.
- Anders Björn and Hans Riesel, Table errata to "Factors of generalized Fermat numbers", Math. Comp. 74 (2005), no. 252, p. 2099.
- Anders Björn and Hans Riesel, Table errata 2 to "Factors of generalized Fermat numbers", Math. Comp. 80 (2011), pp. 1865-1866.
- OEIS Wiki, Generalized Fermat numbers
Crossrefs
Programs
-
Magma
SetDefaultRealField(RealField(400)); IsInteger := func
; [n: n in [2..408] | IsPrime(k) and IsInteger(Log(2, Modorder(7, k))) where k is 3*2^n+1]; -
Mathematica
lst = {}; Do[p = 3*2^n + 1; If[PrimeQ[p] && IntegerQ@Log[2, MultiplicativeOrder[7, p]], AppendTo[lst, n]], {n, 3912}]; lst