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a(n) = prime(n)^2 mod prime(n+2).
1

%I #21 May 30 2023 11:25:29

%S 4,2,3,10,2,17,13,13,2,27,18,36,36,47,26,3,64,29,36,64,17,11,2,43,36,

%T 36,36,36,70,62,100,64,144,144,64,144,100,100,144,64,144,144,36,36,

%U 196,130,29,36,36,100,64,144,256,144,144,64,64,100,36,144,269,13,36,36,324,63,256,144,36,100,196,196,144,100,100,196

%N a(n) = prime(n)^2 mod prime(n+2).

%H Harvey P. Dale, <a href="/A179394/b179394.txt">Table of n, a(n) for n = 1..1000</a>

%e a(1)=2^2 mod(5)=4 mod(5)=4.

%e a(2)=3^2 mod(7)=9 mod(7)=2.

%e a(3)=5^2 mod(11)=25 mod(11)=3.

%e a(4)=7^2 mod(13)=49 mod(13)=10.

%t PowerMod[#[[1]],2,#[[3]]]&/@Partition[Prime[Range[80]],3,1] (* _Harvey P. Dale_, May 30 2023 *)

%o (PARI) a(n) = prime(n)^2 % prime(n+2) \\ _Michel Marcus_, Aug 06 2013

%Y Cf. A167770 has a similar sequence generation rule.

%K nonn

%O 1,1

%A _Umut Uludag_, Jan 07 2011

%E General formula corrected by Umut Uludag