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A272903 Least nonnegative integer x such that n^2+nx-2n-x is prime. 1
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, 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, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

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

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.

LINKS

Cody M. Haderlie, Table of n, a(n) for n = 2..10000

MATHEMATICA

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

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 *)

CROSSREFS

Sequence in context: A219923 A286950 A210638 * A321458 A226194 A053692

Adjacent sequences:  A272900 A272901 A272902 * A272904 A272905 A272906

KEYWORD

nonn

AUTHOR

Cody M. Haderlie, May 09 2016

STATUS

approved

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Last modified August 1 02:28 EDT 2021. Contains 346377 sequences. (Running on oeis4.)