A086124 Primes generated by linear recursion: f(n) = prime(n) * f(n-1) + 2, f(1) = 1.

5, 191, 8831183, 559832762721564181, 3655022053493602810873312808337814473758207442937

Offset: 1

Author

Labos Elemer, Jul 23 2003

Keywords

• nonn

Comments

f(n) = 1, 5, 27, 191, 2103, 27341, 464799, 8831183, 203117211, ... .

a(6) has 298 decimal digits.

Crossrefs

Cf. A000668, A076481, A086122, A086123, A086125.

Programs

Mathematica

f[x_] := Prime[x]*f[x-1]+2; f[1]=1; Do[s=f[n]; If[PrimeQ[s], Print[n]], {n, 1, 1000}]

Formula

a(n) = f(A086125(n)).