A066940 - OEIS

%I #16 Dec 10 2024 11:13:43

%S 2,3,5,6,7,10,11,12,13,17,18,20,21,24,25,26,28,29,30,33,35,36,37,41,

%T 42,43,44,45,49,50,52,53,57,58,59,60,61,64,65,66,67,68,69,70,73,74,77,

%U 78,79,81,82,83,84,87,88,89,98,99,100,101,104,105,106,109,110,111,112,113

%N Numbers k such that gcd(prime(k+1) + 1, prime(k) + 1) = 2.

%C Numbers k such that A063086(k) = 2. - _Andrew Howroyd_, Dec 10 2024

%H Harry J. Smith, <a href="/A066940/b066940.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[ Range[120], GCD[ Prime[ # + 1] + 1, Prime[ # ] + 1] == 2 & ]

%o (PARI) isok(k) = { gcd(prime(k+1) + 1, prime(k) + 1) == 2 } \\ _Harry J. Smith_, Apr 09 2010

%Y Cf. A063086, A066941, A066942, A066943, A066944, A067603, A067604.

%K nonn

%O 1,1

%A _Benoit Cloitre_, Jan 24 2002

%E Edited by _Robert G. Wilson v_, Feb 01 2002