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2^n == 3n+2 (mod n^2-2n).
1

%I #11 Oct 21 2024 17:22:27

%S 3,5,7,13,19,31,43,61,73,103,109,139,151,181,193,199,229,241,271,283,

%T 313,349,421,433,463,523,563,571,601,619,643,645,647,661,811,823,829,

%U 859,883,1021,1033,1051,1063,1093,1105,1153,1231,1279,1291,1303,1321,1429

%N 2^n == 3n+2 (mod n^2-2n).

%C Consists of n such that each of n and n-2 are either prime (A000040) or Sarrus pseudoprimes (A001567).

%C Includes the upper twin primes (A006512).

%H David W. Wilson, <a href="/A206023/b206023.txt">Table of n, a(n) for n = 1..10000</a>

%t Join[{3,5},Select[Range[6,1500],PowerMod[2,#,#^2-2#]==3#+2&]] (* _Harvey P. Dale_, Oct 21 2024 *)

%Y Cf. A000040, A001567, A006512.

%K nonn

%O 1,1

%A _David W. Wilson_, Feb 02 2012