A096848 Primes arising in A096847.
2, 5, 17, 233, 683, 769, 4013, 5039, 28649, 29663, 24917, 15173, 24179, 105509, 252971, 81083, 871289, 941429, 639701, 199193, 713681, 768389, 873569, 1300813, 1308299, 1019687, 4459667, 1477139, 642779, 3953591, 2040443, 8445707, 4906973
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
Do[s=n*DivisorSigma[0, n]-DivisorSigma[1, n];If[PrimeQ[s], Print[{n, s}];ta[[u]]=n;tb[[u]]=s;u=u+1], {n, 1, 1000000}];ta s[n_] := Module[{f = FactorInteger[n], p, e}, p = f[[;; , 1]]; e = f[[;; , 2]]; n * Times @@ (e + 1) - Times @@ ((p^(e + 1) - 1)/(p - 1))]; q[n_] := PrimeQ[s[n]]; seq[lim_] := Module[{m1 = Floor[Sqrt[lim/2]], m2 = Floor[Sqrt[lim]/2]}, s /@ Join[{3}, Union[Select[2*Range[m1]^2, q], Select[4*Range[m2]^2, q]]]]; seq[200000] (* Amiram Eldar, Feb 14 2025 *)
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