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A272903 Least nonnegative integer x such that n^2+nx-2n-x is prime. 1


%S 2,0,1,1,1,1,5,1,1,1,1,2,1,2,1,1,5,2,1,1,1,4,5,1,17,1,3,1,13,1,1,2,3,

%T 2,1,2,5,1,1,4,1,2,5,1,1,1,13,1,11,1,3,5,1,1,1,1,5,7,1,1,11,2,3,1,1,1,

%U 7,1,3,1,11,3,5,2,3,1,17,3,7,4,3,7,1,3,1,1,3,2,1,3,11,2,1,1,7,1,17,5,9

%N Least nonnegative integer x such that n^2+nx-2n-x is prime.

%C The offset is 2 because n^2+nx-2n-x = -1 for n = 1 and all x.

%C a(n) seems to be exclusively prime or a product of two previous terms, and less than n excluding n = 2. x is most frequently equal to 1.

%H Cody M. Haderlie, <a href="/A272903/b272903.txt">Table of n, a(n) for n = 2..10000</a>

%t Table[Min[DeleteCases[Table[If[PrimeQ[n^2+n*x-2n-x],x],{x,0,n}],Null]],{n,2,100}] (*Assuming that x<n.*)

%t lni[n_]:=Module[{x=0},While[!PrimeQ[n^2+n*x-2n-x],x++];x]; Array[lni,100,2] (* _Harvey P. Dale_, May 12 2019 *)

%K nonn

%O 2,1

%A _Cody M. Haderlie_, May 09 2016

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