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, 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, 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, 2, 3, 1, 1, 5, 3, 2, 2, 2, 3, 2, 2, 6, 4, 1, 2, 3, 4

Offset: 1

Author

Pierre CAMI, Nov 07 2011

Keywords

• nonn

Comments

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

Links

• Pierre CAMI, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A199323, A199324.

Programs

Mathematica

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 *)