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Primes of the form k! + k^2 + 1.
1

%I #23 Sep 08 2022 08:45:25

%S 2,3,7,41,757

%N Primes of the form k! + k^2 + 1.

%C Primes of the form A004664(k) + 1.

%C For k! + k^2 + 1 to be prime, k > 1, it is necessary but not sufficient for k to be even.

%C No more terms for k < 1150. [_Vincenzo Librandi_, Dec 22 2010]

%F A000040 INTERSECTION A227546 = primes INTERSECTION {k! + k^2 + 1}.

%t lst={}; Do[s=n!+n^2;If[PrimeQ[p=s+1], AppendTo[lst, p]], {n, 0, 5!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Sep 27 2008 *)

%o (Magma) [ a: n in [0..1150] | IsPrime(a) where a is Factorial(n)+n^2+1 ]; // _Vincenzo Librandi_, Dec 22 2010

%Y Cf. A000040, A004664, A119448.

%K nonn

%O 1,1

%A _Jonathan Vos Post_, Jul 28 2006