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A180172 a(n) = gcd(prime(n)+2, n). 2

%I #11 Mar 12 2023 04:08:15

%S 1,1,1,1,1,3,1,1,1,1,11,3,1,1,1,1,1,9,1,1,3,1,1,1,1,1,3,1,1,5,1,1,1,1,

%T 1,9,1,1,13,5,1,3,1,1,1,1,1,3,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,5,11,1,

%U 1,1,1,71,1,1,1,3,1,1,3,1,1,1,1,1,3,1,1,1,1,1,15,7,1,3,1,1,1,1,1,3,1,1,1,1

%N a(n) = gcd(prime(n)+2, n).

%H G. C. Greubel, <a href="/A180172/b180172.txt">Table of n, a(n) for n = 1..10000</a>

%t Table[GCD[n,Prime[n]+2],{n,200}]

%o (Magma) [GCD(n,NthPrime(n) +2): n in [1..110]]; // _G. C. Greubel_, Mar 12 2023

%o (SageMath) [gcd(nth_prime(n) + 2, n) for n in range(1,111)] # _G. C. Greubel_, Mar 12 2023

%Y Cf. A003989, A052147, A084309, A084310, A180173.

%K nonn

%O 1,6

%A _Zak Seidov_, Aug 15 2010

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Last modified April 24 18:17 EDT 2024. Contains 371962 sequences. (Running on oeis4.)