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 A199322 Number of twin prime numbers of the form n*(n+1) + 2*k-3 and n*(n+1) + 2*k-1 with k = 1 to n+1. 1

%I

%S 1,1,2,0,1,1,1,1,2,0,2,1,2,1,2,1,1,1,0,2,1,1,1,3,1,0,1,3,1,0,3,2,1,1,

%T 4,0,2,2,2,2,2,2,2,2,5,1,3,1,0,2,4,2,0,2,2,3,4,3,3,2,2,4,4,5,1,4,2,3,

%U 2,3,1,1,5,3,2,2,2,3,2,2,6,4,1,2,3,4

%N Number of twin prime numbers of the form n*(n+1) + 2*k-3 and n*(n+1) + 2*k-1 with k = 1 to n+1.

%C 0.66*n/log(n)^2 is a good approximation for a(n) as n increases

%H Pierre CAMI, <a href="/A199322/b199322.txt">Table of n, a(n) for n = 1..10000</a>

%t Table[m = n*(n+1); Length[Select[Range[n+1], PrimeQ[m + 2*#-3] && PrimeQ[m + 2*#-1] &]], {n, 100}] (* _T. D. Noe_, Nov 07 2011 *)

%Y Cf. A199323, A199324.

%K nonn

%O 1,3

%A _Pierre CAMI_, Nov 07 2011

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Last modified December 8 22:49 EST 2021. Contains 349596 sequences. (Running on oeis4.)