1,1

One less than the associated number in A153039; one more than that in A153043. - R. J. Mathar Dec 20 2008

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Let p = prime number n = (p^2+5)/2 mod (p)

Select[Range[4, 200], !PrimeQ[2*#-5]&] (* Vladimir Joseph Stephan Orlovsky, Feb 09 2012 *)

(MAGMA) [n: n in [4..120]|not IsPrime(2*n-5)] // Vincenzo Librandi, Aug 30 2012

Cf. A089253, A153039.

Sequence in context: A089373 A184114 A295797 * A024888 A226567 A184106

Adjacent sequences: A153037 A153038 A153039 * A153041 A153042 A153043

nonn,easy

Vincenzo Librandi, Dec 17 2008

Flipped sign in definition. - R. J. Mathar, Dec 20 2008

approved