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%I #23 Dec 09 2024 23:23:33
%S 1,4,6,2,12,2,18,2,4,30,4,2,42,2,4,2,60,2,2,72,2,2,4,6,2,102,2,108,2,
%T 6,2,4,138,4,150,4,2,2,4,2,180,2,192,2,198,10,2,2,228,2,2,240,2,4,2,4,
%U 270,4,2,282,4,6,2,312,2,6,4,2,348,2,2,6,4,2,2,4,6,2,6,2,420,2,432,2,2
%N a(n) = gcd(prime(n+1) - 1, prime(n) + 1).
%H Harry J. Smith, <a href="/A066984/b066984.txt">Table of n, a(n) for n = 1..1000</a>
%t GCD[#[[1]]+1,#[[2]]-1]&/@Partition[Prime[Range[90]],2,1] (* _Harvey P. Dale_, May 16 2021 *)
%o (PARI) a(n) = { gcd(prime(n+1) - 1, prime(n) + 1) } \\ _Harry J. Smith_, Apr 15 2010
%K nonn,changed
%O 1,2
%A _Benoit Cloitre_, Jan 27 2002